A lot of Christians disagree with Calvinists. So what? Protestants are united on what constitutes salvation - God's grace alone through faith alone in Christ alone.
Roman Catholics put themselves outside the historic, orthodox Christian faith by praying to a "co-redeemer" and foloowing "another Christ."
No one that I know teaches "pre-damnation." All men are called to kneel to Christ and believe in Him as Lord, God and Savior. Without Christ, all men are lost because all men are fallen. Without the free gift of the indwelling Holy Spirit, none of us would be saved.
Salvation is a free gift of grace, not of works, lest anyone boast.
Rome boasts.