Calvin misunderstood "Predestined"

Calvin thought & taught that Predestination meant that if one joins the church they were "predestined" before birth to be saved and if one didn't, they were Predestined before birth to be lost.

This a WRONG. 

Calvin's Error allows for no free will.....how Predestination actually works is as follows:
God had the Plan of Redemption in place so those who would choose to follow Him could be saved.
It was His Predestined Plan of Redemption.....

"...we are “predestinated [previous boundaries set] . . . unto the adoption of children by Jesus Christ to Himself” (Ephesians 1:5). And “if children, then heirs; heirs of God, and joint-heirs with Christ” (Romans 8:17).
Furthermore, we have been “accepted in the beloved” (Ephesians 1:6). That word, “accepted,” is a specialized form of the word most often translated “grace.” 

We have been “graced” by almighty God, who has set absolute boundaries around our lives and made us His children. We were purchased “through His blood” (v. 7) “that he might redeem us from all iniquity, and purify unto Himself a peculiar [that is, ‘precious’] people, zealous of good works” (Titus 2:14)."
HMMIII