The foundation of Calvinist/Reformed theology is the doctrine of Total Depravity or Total Inability that states the unregenerated man cannot receive or understand spiritual matters and therefore cannot believe on Christ. The text proof for this is 1 Cor 2:14. But is this what the scriptures really teach? Consider 1 Cor 14; 1 Cor 14:23 If therefore the whole church be come together into one place, and all speak with tongues, and there come in those that are unlearned, or unbelievers, will they not say that ye are mad? 24 But if all prophesy, and there come in one that believeth not, or one unlearned, he is convinced of all, he is judged of all: 25 And thus are the secrets of his heart made manifest; and so falling down on his face he will worship God, and report that God is in you of a truth. In this chapter, Paul is rebuking these Corinthians for their abuse of the spiritual gift of tongues, and showing the advantage of speaking in words easily to be understood. Note that Paul says if an unbeliever comes in and hears all the church speaking in unknown (to him) tongues, he will think all the members of the church are insane. But if he hears words that are easy to be understood, he will be CONVINCED by all, and convicted (secrets of his heart made manifest) and he will fall on his face and WORSHIP GOD. So, we see here that an unbeliever can be taught, convinced, and convicted to believe in Christ. There is no mention of a supernatural regeneration here, it says the man will be CONVINCED. This agrees with Christ's statement in John 6:45 where he says those who have heard, been taught, and learned from the Father shall come to him. Jhn 6:45 It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me. No man can come unto Jesus unless he has been taught by the Father. This is the very point Paul is making in 1 Corinthians 14, that the church should teach in words and language that are easy to be understood. Paul also shows that unbelievers can be convinced and convicted by this simple preaching resulting in that they will fall down and worship God. So, the scriptures do not teach that unbelievers cannot understand the preaching of the gospel.