Within theology, legalism is an overemphasis on conduct and good deeds, via "keeping the law", as opposed to grace. Depending on the group, the "law" is defined differently: some groups define it as the Old Testament requirements (mainly the dietary laws and worship on Saturdays, the original Sabbath), while others define it in terms of the group's historical teachings and personal preferences.
There are two variants of legalism:
- The first teaches that keeping the law is mandatory for ultimate eternal salvation. This variant is commonly held by groups considered cults e.g. Jehovah's Witnesses, Mormons, Seventh-Day Adventists), and is generally rejected by most Christians, as it is the opposite of Sola Fide, which maintains the view that belief in Jesus Christ is the only way one can obtain eternal life.
- The other variant teaches that a Christian should conduct himself/herself in a Godly manner, but in doing so emphasizes certain external requirements (e.g. women not wearing pants or jeans, men having short hair and no facial hair, not using alcohol or tobacco, avoiding secular movies or music or even television completely, requiring adherence to Old Testament dietary laws), often to a level above Biblical standards themselves, and even to the point that failure to do so can result in removal from a congregation. Groups holding to this variant do not believe that failure to maintain the requirements will result in loss of salvation, but that it presents a poor witness (or may be proof of lack of real salvation in the first place). This variant is commonly held by fundamentalist churches and groups.
The term "legalism" or "legalist" is also used as a pejorative by persons (both Christians and non-Christians) who dislike Christians telling them about their sins, and thus label the other person as such, even when the other person is not holding to extreme views as listed above.