RCC & Grace Alone
The modern Roman Catholic church clearly embraces a heretical form of Semi-Pelagianism which affirms that man has a need for God's grace (for man is too weak to help himself), but man by his own free will is able to decide whether he wants God's grace. Whereas Pelagius taught that salvation is totally man's own doing, and Augustine taught that salvation is totally from God, Semi-Pelagianism teaches that salvation is a combination of the efforts of both man and God. According to RCC Semi-Pelagianism, salvation is accomplished when man decides to co-operate with God and accepts the grace God offers him. and also must maintain his own just standing before God by merit and good works. This is often viewed as a synergistic concept of salvation. Whereas Reformed Protestants also affirm the necessity of good works, yet they are the inevitable result of salvation, not the cause of it.
By Scripture
Old Testament