The Encyclopedia of Christianity in the United States defines "legalism" as a pejorative descriptor for "the direct or indirect attachment of behaviors, disciplines, and practices to the belief in order to achieve salvation and right standing before God," emphasizing a need "to perform certain deeds in order to gain salvation" as opposed to a belief in salvation through the grace of God, "bestowed upon the individual through faith in Jesus Christ." Additionally, "legalism" pejoratively refers to the view, held by some fundamentalist Christians, that Christians should not engage in social practices which are perceived as being contrary to Christian witness, such as gambling, dancing, consuming alcohol, enjoying secular entertainment, or wearing immodest clothing.
The Pharisees and Sadducees, as described in the Gospels, are often regarded by Christians as legalists. Historically, many Christian New Testament scholars attacked Judaism for supposedly being "legalistic"; this accusation has been rebutted by other scholars, such as E. P. Sanders, who identify this criticism as inaccurate and ahistorical.
In 1921, Ernest De Witt Burton stated that in Gal. 2:16, the Greek word nomos was "evidently used ... in its legalistic sense, denoting divine law viewed as a purely legalistic system made up of statutes, on the basis of obedience or disobedience to which individuals are approved or condemned as a matter of debt without grace. This is divine law as the legalist defined it."
- The Quadrilog: Tradition and the Future of Ecumenism: Essays in Honor of George H. Tavard, ed. Kenneth Hagen (Liturgical Press, 1994), p. 84.
- Robert W. Bertram, "Scripture and Tradition" in the Lutheran Confessions, Pro Ecclesia: A Journal of Catholic and Evangelical Theology (Vol. 10), Center for Catholic and Evangelical Theology (spring 2001).
- Benjamin Espinoza, "Legalism" in Encyclopedia of Christianity in the United States, eds. George Thomas Kurian & Mark A. Lamport (Rowman & Littlefield, 2016), p. 1338.
- E. P. Sanders, "Jesus, Ancient Judaism, and Modern Christianity: The Quest Continues" in Jesus, Judaism, and Christian Anti-Judaism: Reading the New Testament After the Holocaust, eds. Paula Fredriksen & Adele Reinhartz (Westminster John Knox Press, 2002), pp. 48-52.
- Mason Olds, "Joseph Fletcher Revisited" in Biomedical Ethics: Humanist Perspectives of Humanism Today, ed. Howard B. Radest (Prometheus Books, 2006), p. 127.
- Joseph F. Fletcher, Situation Ethics: The New Morality (Westminster John Knox Press, 1966), p. 17.
- Burton, Ernest De Witt, The International Critical Commentary, Galatians, 1921, p. 120.