The confessions are made by innocent people who are already with God; the confessions are made to escape the hangman's noose.
Their confessions have nothing to do with coming to God, they have to do with satisfying mortal men who believe themselves to be infallible. Those who confess are only trying to save their lives, in fact by confessing to witchcraft, they put their souls in danger, rather than coming closer to God, they put distance between themselves and God by confessing a lie.
The confessions are a true example of irony because they are the exact opposite of what they appear to be.
At one point in Act IV Parris says "Reverend Hale has returned to bring Rebecca Nurse to God." We already know from the description of Rebecca in Act I that she is probably the most holy character in the play. Hale is pleading with them to "confess" to witchcraft to save their lives. Hale is extremely guilt ridden at this point in the play as he was the one who signed many of the death warrants including Rebecca's.
Later in Act IV, Hale admits that he is counseling them to lie to save themselves. He says, "I come to do the Devil's work. I come to counsel Christians they should belie themselves. There is blood on my head! Can you not see the blood on my head!"
In Act I, he was the one who urged Tituba to confess to witchcraft. At that point in the play, he thought he really was bring them to God. Throughout the play he saw Abigail's lies and her motives for accusing Elizabeth. By the end of the play he had made a complete turn around was urging people to lie to save themselves. He was urging them to sin to save themselves from being hanged.
Additionally, by lying and "admitting" that they were practicing witchcraft, they are not "coming to God" at all, but rather coming to a theocratic government that claims to work in the name of God, but really themselves seem to have forgotten what their faith asks them to do. The kindness, compassion, and forgiveness so important to their faith seems to have been totally wiped from their minds when considering the manner in which they treat the townspeople. By asking these people to "come to God", they are really steering them towards damnation in that they must lie (which is a sin) in order to give what they are asked to give, and in order to save their lives. The question then becomes, is it worse to keep your pride and honesty and die, thus giving up life which God's greatest gift, OR is it worse to lie and save the life God has given you?
It is also important to note that those who are "coming to God" and confessing to the sin of witchcraft have not actually been practicing witchcraft. Not only are they being selfish in "saving their own skins" rather than standing up for the truth, they are lying, not only to themselves, but to the whole community, and elected religious figures. Knowingly lying seems to have very little to do with "coming to God". THe ones who do tell the truth (and come to or sty with God) are condemn to death, and presumably, in popular opinion, hell.
The motives of characters who confess to witchcraft have very little to do with saving their souls and much more to do with saving their earthly lives. They are not "coming to God" in spiritual repentance and hopes of salvation; they simply want to get out of prison and not be hanged. Thus the idea of "coming to God" might be better called "saving their own skins".