To Catholics, faith in Christ is only the beginning of salvation, and the individual must engage in good works for eternal salvation. Purgatory, for example, is where man goes after death if he did not sufficiently pay for his sins.
While Protestants recognise the importance of good works, they believe good works is the fruit of their salvation and not part of the process to be saved.
"Simply put, the Roman Catholic viewpoint on salvation implies that Christ's atonement on the cross was not sufficient payment for the sins of those who believe in Him, and that even a believer must atone or pay for his own sins, either through acts of penance, or time in purgatory," wrote Got Questions Ministries in its Web site.
Differences aside, Protestants and Catholics do share several core beliefs including the Trinity, the deity of Jesus, and the fact that he was sinless, that he died on the cross for man's sin and rose from the dead and ascended to heaven.
"When you're talking to Catholics, you don't have to convince them to believe in God, Jesus Christ or the Bible," noted NAMB's Davis.
Still, the divide between Protestants and the Roman Catholic Church is clear, as respected theologian Dr R Albert Mohler recently reiterated.
"I am convinced that he (the pope) is not right - not right on the papacy, not right on the sacraments, not right on the priesthood, not right on the Gospel, not right in understanding the Church," the seminary president wrote recently in a special column for The Washington Post and Newsweek.
"The Roman Catholic Church believes that evangelicals are in spiritual danger for obstinately and disobediently excluding ourselves from submission to its universal claims and its papacy. Evangelicals are concerned that Catholics are in spiritual danger for their submission to these very claims," he added.
"We both understand what is at stake."
According to the CIA World Factbook, Christians make up one-third of the world's population, with Roman Catholics making up 17 percent, Protestants 5.8 percent, Orthodox 3.5 percent, and Anglicans 1.3 percent. By comparison, Muslims make up 21 percent, Hindus 13.3 percent and Buddhists 5.8 percent.
Christian Today reporter Eric Young contributed to this article.
