There are many people I know, like Lee Strobel and Josh McDowell, who testify that they went through a process of weighing the facts and evidence of the scripture's claims before coming to faith. In other words, it didn't really happen in an instant. Their faith was established over a period of months or even years of research and deliberation. They testify that the evidence was overwhelming and lead them to leave their doubts and place their faith in Christ. Their books, "A Case for Christ" and "Evidence that Demands a Verdict" have lead many intellectual doubters to faith in Christ over the years. This along with the scriptural evidence that Paul used much persuasion to lead some of his Jewish brethren to faith (Acts 28 etc) leads me to question the idea that there is one instant act of regeneration that miraculously births a new nature with new desires. New believers notoriously struggle with their old sinful desires and struggle with doubt. These experiences suggest that the act of regeneration is a birth of the Holy Spirit (as seen at Pentecost) within the hearts of those who believe. The HS begins the process of sanctification by which the man is conformed to the image of Christ OVER A PERIOD OF TIME. This NEW NATURE with NEW DESIRES is not something that happens overnight, but is a process by which man's faith is strengthened and his nature is conformed. If Regeneration does as it claims in the Calvinistic system, then what does Sanctification accomplish that the work of Regeneration has not? In other words, if the act of Regeneration irresistible causes a man to repent and believe because of the new nature, then why does it fail to irresistibly cause a man to stop lusting or lying immediately? Isn't belief in Christ and repentance more difficult than resisting sin? How can the new nature be "good" enough to have faith in Christ, but not good enough to resist sin at least as well as anyone else who has that same new nature?