What do the scriptures show?
John 20:29 Jesus saith unto him, Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed.
Do you see any magic here? Jesus himself said Thomas believed because he saw him.
John 1:50 Jesus answered and said unto him, Because I said unto thee, I saw thee under the fig tree, believest thou? thou shalt see greater things than these.
How about here? Do you see some magical regeneration that caused Nathanael to believe?
John 4:39 And many of the Samaritans of that city believed on him for the saying of the woman, which testified, He told me all that ever I did.
How about here? Did the woman at the well have the supernatural ability to make the men of her town believe?
John 4:40 So when the Samaritans were come unto him, they besought him that he would tarry with them: and he abode there two days.
41 And many more believed because of his own word;
42 And said unto the woman, Now we believe, not because of thy saying: for we have heard him ourselves, and know that this is indeed the Christ, the Saviour of the world.
Again, anything magical here, or does it say they believed Jesus simply because of his words?
John 2:23 Now when he was in Jerusalem at the passover, in the feast day, many believed in his name, when they saw the miracles which he did.
It does say Jesus performed miracles here, but not that he supernaturally regenerated these persons, it says they believed because they saw his miracles.
John 8:30 As he spake these words, many believed on him.
What caused them to believe?
Acts 9:42 And it was known throughout all Joppa; and many believed in the Lord.
Peter had just raised Dorcas from the dead, and the news of this spread through Joppa. Did those who told others have power to regenerate others?
Acts 18:8 And Crispus, the chief ruler of the synagogue, believed on the Lord with all his house; and many of the Corinthians hearing believed, and were baptized.
Again, anything magical here?
I could probably show you at least ten more examples, but I think you get the drift.
Men have the ability to believe, although no man could possibly believe in Jesus unless they have heard of him. Men can believe by seeing miracles, men can believe by being convinced or persuaded by sound arguments from scripture, men can believe by hearing the testimony of others.
Men cannot believe in a vacuum, but men can believe in Jesus when he is revealed to them. This revelation comes from God, therefore God gets all the credit. Without this revelation all men would be in utter darkness and could not possibly believe. But God doesn't have to magically change a man's soul to believe, all men are created with the God given ability to believe.