Well, first you have to distinguish between doctrines of predestination. What you are talking about sounds like double predestination, which is what (at least some) Calvinists believe. Other Protestants believe in conditional predestination.
Essentially, conditional predestination is the belief that God knows everything and predestined those for election who will choose to have faith in Him. God predestines based on the fact that He knows what choice the person will make, but whether an individual chooses eternal life or eternal damnation is that person’s choice. So God predestines to save those who will believe on Him and repent, which (because He is God) He already knows beforehand.
Double predestination says that God chooses who will go to heaven and who will go to hell, and this decision is not based on the worthiness of the individual since all individuals are unworthy. God’s decision to save some and damn others is based entirely on His mercy to save those who He will.
