John Calvin, an eminent Protestant theologian, taught that particular individuals were elected and predestined by God to be saved and all others were predestined to be lost. Essentially, this meant that their wills were constrained by a work of God. It also meant that nothing which the individuals did could reverse this election. 

This teaching is a basic of the Presbyterian Church today.

It is plain that there is an election as it is taught in Ephesians and in Romans as well as elsewhere. But it is also clear that Christians can forsake their state of grace by protracted acts of the will in which they apostatize the faith. This is taught in numerous places, particularly in Hebrews 6. How are these teachings to be reconciled? 

My belief is that indeed there is an election and Christians are predestined to be saved but my belief is that this election is a corporate election; not an individual election. In other words, God has elected that all who willingly trust Christ and continue in the faith are elected. There is an election from before the foundation of the world that all who trust Christ will be saved. It is much like a train. Election is a train conveying men to eternal life. All who remain on the election train will reach the destination of Heaven. All who decide to forsake their destination may leave the train at their peril. No force on earth or hell can force anyone off the train but anyone on the train may decide of their own accord to leave.

This is the only way the clear teachings against apostasy can be understood and have any meaning. Otherwise, the warnings against falling away have no meaning. There are those who would say that the warnings are the means of insuring that the elect remain on the train and that anyone who ignores the warnings was never on the train to begin with. This is an attractive idea but is simply contrary the clear teachings of the warnings themselves.