In Christian theology, synergism is the belief that salvation involves some form of cooperation between divine grace and human freedom. Synergism is upheld by the Roman Catholic Church, Orthodox Churches, Anabaptist Churches and Methodist Churches. It is an integral part of Arminian theology common in the General Baptist and Methodist traditions.

Synergism stands opposed to monergism (which rejects the idea that humans cooperate with the grace of God), a doctrine most commonly associated with the Reformed Protestant as well as Lutheran traditions, whose soteriologies have been strongly influenced by the North African bishop and Latin Church Father Augustine of Hippo (354–430). Lutheranism, however, confesses a monergist salvation but rejects the notion that anyone is predestined to hell (see § Lutheran and Calvinist views).

Synergism and semipelagianism each teach some collaboration in salvation between God and humans, but semipelagian thought teaches that the beginning half of faith is an act of human will. The Council of Orange (529), Lutheran Formula of Concord (1577), and other local councils each condemned semipelagianism as heresy.