and you don’t know if you’re one of them? That's not what they say.
Assurance for the believer is part of the package. If you trust in Christ you can know you are saved.
Predestination, in theology is the doctrine that all events have been willed by God. John Calvin interpreted biblical predestination to mean that God willed eternal damnation for some people and salvation for others.
So again I ask how do you know if you're one of them.