Our church has spent quite a bit of time recently studying Mormonism.  We intend to go on and study Islam.  One thing I have been convinced of before and after these studies is the importance of understanding the basics of Christianity.

For example, every Christian should know and understand the Five Solas.  These doctrines are important for understanding the Christian faith and also for defending against cults and false religions.  Think of how cults and false religions are exposed by each of the Five Solas:

• Sola Scriptura (Scripture Alone): Cults and false religions try to substitute some human authority in the place of God's Word.  The Mormons have the Book of Mormon, Doctrine & Covenants, the Pearl of Great Price and the teachings of the prophets and apostles.  The Jehovah's Witnesses have the Watchtower Society.  Christians have the Bible alone (2 Tim. 3:16-17).
• Sola Gratia (Grace Alone):  Every religious system the world has ever known has claimed to provide a way for man to either ascend into heaven by his own efforts or to become a god himself.  The Mormons believe that "As man is God once was and as God is man may become" based on our worthiness.  It's interesting that Mormonism turns the Bible's teaching upside down: rather than the Bible's teaching that God saves men on the basis of grace; Mormonism teaches that men become gods on the basis of our good works.  Mormonism worships false gods and preaches a false gospel.
• Sola Fide (Faith Alone): Even though Joseph Smith re-wrote Romans 4:16 to say that justification rests on "faith and works," God's real word is clear that we are saved by grace through faith and not by works (Rom. 4:16; Eph. 2:8-9).
• Solus Christus (Christ Alone): The Bible teaches that Christ is the only way to salvation because of the uniqueness of His person and atoning work (John 14:6; Acts 4:12; 1 Tim. 2:5).  By believing in Christ, the Christian receives the very righteousness of God (Phil. 3:9-10).  This means that we must believe in the biblical Jesus.  The Jehovah's Witnesses teach that Jesus is not God, that He is instead Michael the archangel.  Mormonism teaches that Jesus is the brother of Lucifer and that Jesus was conceived by the Heavenly Father having sex with Mary.  Only the biblical Jesus saves (2 Cor. 11:4).
• Soli Deo Gloria (to the glory of God alone): Cults and false religions glorify people, whether it's their members, their leaders, or someone else.  But the Bible is clear that everything exists to the glory of God (Rev. 4:11) and that human salvation in particular brings glory to God alone (Eph. 1:6; Rom. 11:36).

In summary, we should definitely be aware of what cults and false religions are teaching (Jude 3; 1 John 4:1), but even more importantly, we need to understand what the Christian message is.