The problem with Calvinism: It is forced to conclude that a person must first be in Christ before he ever believes in Christ, in order to have access to what is in Christ, namely the new regenerate heart in order to unfailingly come to Christ. Calvinism requires that a person must become preemptively in Christ, apart from repentance and apart from believing in Christ, in order to gain access to the regenerated new heart which is alone reserved in Christ.
For Calvinism to teach that certain people are regenerated in Christ, apart from the basis of believing in Christ, while also trying to juggle salvation by faith, Calvinists must also hold that a person who is in Christ remains unsaved until he exercises faith in Christ. So how can a person who is “born again in Christ” even for one instant of time, remain lost in sin?