Only the Holy Spirit can convert. Only the Holy Spirit can change the disposition of the soul and regenerate that person who is dead in sin and trespasses.

Dr. R. C. Sproul: The sad abuse is that it gives multitudes of people a false sense of security who think that they’re saved because they raised their hand or prayed a prayer or walked an aisle. You know Edwards preached that sermon a warning to professors (it was not a warning to academic teachers). It was to those who had made a profession of faith and who believed that because they made a profession of faith that they were saved. Now everybody who is saved is called to make a profession of faith, but Jesus warned again and again and again many will come to Me on that last day saying “Lord, Lord, didn’t I do this, didn’t I do that?” And He will say, “Depart from Me you workers of iniquity. I never knew you.”

You are not justified by a profession of faith. You’re justified by a possession of it. And you can’t manipulate that. Only the Holy Spirit can convert. Only the Holy Spirit can change the disposition of the soul and regenerate that person who is dead in sin and trespasses. We can’t force that, and when we do, we put people at everlasting peril when we give them a false sense of security.

The Question of Altar Calls
A Transcript: From the second Question and Answer session at "The Truth of the Cross - 2014 Regional Ligonier Conference"