But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned (1 Cor. 2:14)
It is a choice to be a “natural man” as no one is born a sinner. It is rather an adopted nature just as the context indicates. An alcoholic might suggest that he has inherited genes that makes him an alcoholic out of necessity just like his parents, but even though genetics can partly explain certain similar weaknesses/attitudes/traits we still cannot blame our actions – like repeatedly pouring liquor into a glass and drink – on our parents. “Natural” in 1 Cor. 2:14 is a translation from the Greek adjective psychikos (Strong’s 5591) and can be translated as natural or sensual. The word is used 6 times in the New Testament. In 1 Cor. 15 we have a slightly different perspective of the word, because the passage talks about the resurrection when we will get rid of our fleshly bodies to get new spiritual bodies prior to entering the kingdom of God:
1 Cor. 15:33 Be not deceived: evil communications corrupt good manners.34 Awake to righteousness, and sin not; for some have not the knowledge of God: I speak this to your shame.—44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
James makes it clear that we should not mix righteous deeds with unrighteous deeds. Just like Paul he urges his readers to stop sinning:
Ja. 3:10 Out of the same mouth proceedeth blessing and cursing. My brethren, these things ought not so to be.11 Doth a fountain send forth at the same place sweet water and bitter?—14 But if ye have bitter envying and strife in your hearts, glory not, and lie not against the truth.15 This wisdom descendeth not from above, but is earthly, sensual, devilish.16 For where envying and strife is, there is confusion and every evil work.
We can see that those who are “natural” are those who choose to walk after their own lusts instead of having an interest to be led by the Spirit. It usually concerns those who have no desire to seek God (as per Rom. 1:18-32) and who are therefore atheists/agnostics, but it could also apply to anyone (also Christians) who chooses to walk after his/her own lusts. They separate themselves from God by following their ungodly lusts:
Jude 1:16 These are murmurers, complainers, walking after their own lusts; and their mouth speaketh great swelling words, having men’s persons in admiration because of advantage.17 But, beloved, remember ye the words which were spoken before of the apostles of our Lord Jesus Christ;18 How that they told you there should be mockers in the last time, who should walk after their own ungodly lusts.19 These be they who separate themselves, sensual, having not the Spirit.20 But ye, beloved, building up yourselves on your most holy faith, praying in the Holy Ghost,21 Keep yourselves in the love of God, looking for the mercy of our Lord Jesus Christ unto eternal life.22 And of some have compassion, making a difference:23 And others save with fear, pulling them out of the fire; hating even the garment spotted by the flesh.
A natural man is again someone who chooses to live after the flesh and not after the Spirit. The context below shows that Paul speaks highly of the power of the holy Spirit which is given to Christians (after repentance), and through this magnificent power it is certainly easier to come closer to God and know all the details of his will. We are able to be victorious over sin if we choose to be led by the Spirit, but it takes a will of our own. Also agnostics are able to avoid sin, but if they decide to repent and start living with Jesus Christ they will get a new power thanks to the new Helper – the holy Spirit. The holy Spirit does not force a person to obey him:
1 Cor. 2:12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.13 Which things also we speak, not in the words which man’s wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual.14 But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.15 But he that is spiritual judgeth all things, yet he himself is judged of no man.
The promise given to us in Gal. 5 is that if we decide to walk in the Spirit, we are automatically not fulfilling the lust of the flesh because of our righteous lives. If we instead live after the flesh, we automatically do not walk in the Spirit since the flesh is contrary to the Spirit. It is one or the other. The Spirit would never lead us unto the road of destruction. Paul assures us that if we do live after the flesh (and he gives examples of what that means) we can forget about inheriting the kingdom of God. He does not say that Christians are exempted from this danger. He also says “If we live in the Spirit, let us also walk in the Spirit”, showing that this is nothing that happens automatically without our participation. It is the responsibility of each individual to live a holy life, and we cannot blame God for preventing us from obeying his commandments:
Gal. 5:16 This I say then, WALK IN THE SPIRIT, AND YE SHALL NOT FULFIL THE LUST OF THE FLESH.17 For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.18 But if ye be led of the Spirit, ye are not under the law.19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,23 Meekness, temperance: against such there is no law.24 And they that are Christ’s have crucified the flesh with the affections and lusts.25 If we live in the Spirit, let us also walk in the Spirit.
Below we can more clearly see what happens to someone who God gives up to a reprobate mind due to the individual’s decision to walk after his own lusts (and become a natural man). Such a person is without excuse because he could have reached out to God and live according to his will, but chose not to. THAT is the reason for deserving a spot in hell. Not because God chose someone to be a wicked non-elect before he was even born, but because the person had all the chances in the world to seek and believe in God (the very purpose for God to create us in the first place as per Acts 17:26-30) but instead turned his back on him and lived a rebellious life.
Rom. 1:18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;19 Because that which may be known of God is manifest in them; for God hath shewed it unto them.20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.22 Professing themselves to be wise, they became fools,23 And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.24 Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves:25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen.26 FOR THIS CAUSE God gave them up unto vile affections: for even their women did change the natural use into that which is against nature:27 And likewise also the men, leaving the natural use of the woman, burned in their lust one toward another; men with men working that which is unseemly, and receiving in themselves that recompence of their error which was meet.28 And even as they did not like to retain God in their knowledge, God GAVE THEM OVER TO A REPROBATE MIND, to do those things which are not convenient;29 Being filled with all unrighteousness, fornication, wickedness, covetousness, maliciousness; full of envy, murder, debate, deceit, malignity; whisperers,30 Backbiters, haters of God, despiteful, proud, boasters, inventors of evil things, disobedient to parents,31 Without understanding, covenantbreakers, without natural affection, implacable, unmerciful:32 Who knowing the judgment of God, that they which commit such things are worthy of death, not only do the same, but have pleasure in them that do them.
It is not a good idea to be a natural man with a carnal mind, because then we simply cannot please God. A person who has his mind set on maintaining his sins cannot at the same time live according to God’s commandments.
Rom. 8:7 Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
We can learn from Paul who those are who “are after the flesh”. They are the ones who walk not after the Spirit but after the flesh. This means that their wicked actions cause them to be carnally minded/natural men. Fortunately there is a solution provided by Paul in that same chapter, and that is to walk after the Spirit which is a much better choice.
Rom. 8:1 There is therefore now no condemnation to them which are in Christ Jesus, WHO WALK NOT AFTER THE FLESH, BUT AFTER THE SPIRIT.—4 That the righteousness of the law might be fulfilled in us, WHO WALK NOT AFTER THE FLESH, BUT AFTER THE SPIRIT.5 For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.6 For to be carnally minded is death; but to be spiritually minded is life and peace.
Paul explains this also in Rom. 6, where he assures us that we can successfully start living according to the Spirit instead of obeying sin. Note that we are slaves to the one we choose to obey, so if we choose to obey sin we are slaves to sin and not free. Paul is writing to the Christians in Rome, so Christians are clearly not freed from the risk of landing in spiritual death – which would happen to anyone who decides to obey sin and who does not repent:
Rom. 6:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.— 12 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof.13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God.14 For sin shall not have dominion over you: for ye are not under the law, but under grace.15 What then? shall we sin, because we are not under the law, but under grace? God forbid.16 Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?17 But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered you.18 Being then made free from sin, ye became the servants of righteousness.19 I speak after the manner of men because of the infirmity of your flesh: for as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.20 For when ye were the servants of sin, ye were free from righteousness.21 What fruit had ye then in those things whereof ye are now ashamed? for the end of those things is death.22 But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life.23 For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.
Paul refers to a passage in Isaiah 29 when it talks about hidden wisdom. The reason for people living in darkness is due to their decision to remove their hearts from him:
1 Cor. 1:18 For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.19 For it is written, I will destroy the wisdom of the wise, and will bring to nothing the understanding of the prudent.*)
*) Isaiah 29:13 Wherefore the Lord said, Forasmuch as this people draw near me with their mouth, and with their lips do honour me, but have removed their heart far from me, and their fear toward me is taught by the precept of men:14 Therefore, behold, I will proceed to do a marvellous work among this people, even a marvellous work and a wonder: for the wisdom of their wise men shall perish, and the understanding of their prudent men shall be hid.15 Woe unto them that seek deep to hide their counsel from the Lord, and their works are in the dark, and they say, Who seeth us? and who knoweth us?
God loves us and wishes that we all would come to the knowledge of the truth:
1 Tim. 2:3 For this is good and acceptable in the sight of God our Saviour;4 Who will have all men to be saved, and to come unto the knowledge of the truth.
You can read about Eph. 2 here, where you will see that it is a choice to be “children of wrath” (individuals who are subject to God’s wrath due to their sins) and that the chapter nowhere suggests that anyone is born that way. It is rather, yet again, about people who choose to walk after their own lusts.