Monergism vs. Synergism
According to definition given in www.monergism.com (emphasis in bold is mine), Monergism is the belief that in our regeneration, the Holy Spirit unites us to Christ independent of any cooperation from our un-regenerated human nature. He quickens us through the outward call cast forth by the preaching of His Word, disarms our innate hostility, removes our blindness, illumines our mind, creates understanding, turns our heart of stone to a heart of flesh — giving rise to a delight in His Word — all that we might, with our renewed affections, willingly & gladly embrace Christ. In Synergism, on the other hand, the grace of God that regenerates us requires our cooperation, through our freedom. Because we have freedom, we can either choose to cooperate or not.
Protestants and “Bible only” Christians who follow the teachings of Reformers Calvin and Luther are monergist, while the rest, together with Catholics (and Eastern Orthodox, to the best of my knowledge) are synergist. A good comparison of these two views is when we have faith in Christ as Lord and Saviour. A monergist will say that our ability to believe in Christ comes solely from God’s Grace – we can do it because we are first regenerated by God, there is no such thing as our cooperation because of our totally corrupt nature. A synergist will say His Grace will first moves us and then we, using our freedom, cooperate by receiving it (or rejecting it). Such cooperation is possible because our nature, while wounded, is not totally corrupted. Note that both in monergism and synergism the initiative for our salvation comes from God.
As one scriptural proof, www.monergism.com cites Ezekiel 11:19-20: And I [God] will give them one heart, and put a new spirit within them; I will take the stony heart out of their flesh and give them a heart of flesh, that they may walk in my statutes and keep my ordinances and obey them; and they shall be my people, and I will be their God. At first glance this verse seems to give strong support of monergism. Let’s look at the next verse, Ezekiel 11:21: But as for those whose heart goes after their detestable things and their abominations, I will requite their deeds upon their own heads, says the Lord God. A monergist will say that God chose them (from eternity) not to be regenerated – the so-called double predestination, i.e. God chose from eternity whom He will regenerate and whom He will not. But how to reconcile it with 1 Corinthians 15:22 (emphasis in bold is mine): For as in Adam all die, so also in Christ shall all be made alive and for the grace of God has appeared for the salvation of all men (Titus 2:11)? Ezekiel 11:19-20 neither explicitly says that regeneration requires or does not require our cooperation and the same applies to other verses cited to support monergism (1 Thessalonians 1:4-5 and 1 Peter 1:23). But does it (1 Thessalonians 1:4) says “he [God] has chosen you”? Does it prove that God chose some men to be saved? Yes, but synergists also believe in Election, i.e. God predestines some men (the Elect) for heaven by choosing them from eternity. But they reject the idea that God predestines the rest to hell. They end up in hell because they, in using their freedom, decide not to cooperate with God’s Grace and not because God desires them to be in hell (Monergist’ view). Scripture says (1 Timothy 2:4) God desires all men to be saved and to come to the knowledge of the truth.