"because the mind set on the flesh is hostile toward God; for it does not subject itself to the law of God, for it is not even able to do so, 8 and those who are in the flesh cannot please God."
If this is the condition of man, then only a supernatural action from God can change it. Predestination basically means that God choses beforehand to save someone, not on a basis of works. So basically, predestination is the only option if by nature humans are hostile towards God, unable to obey or please Him.
Basically, "God, being rich in mercy, because of His great love with which He loved us, 5 even when we were dead in our wrongdoings, made us alive together with Christ (by grace you have been saved)"