Some modern theologians simply assert that efficacious grace means that the performance of a good act by man is due to God's primacy in grace manifesting itself in man's good act. Others identify efficacy with the infallibility of grace in obtaining God's absolute will in creation prior to man's absolute consent: the city of the blessed.

Irresistible grace (also called effectual grace, effectual calling, or efficacious grace) is a doctrine in Christian theology particularly associated with Calvinism, which teaches that the saving grace of God is effectually applied to those whom he has determined to save (the elect) and, in God's timing, overcomes their resistance to obeying the call of the gospel, bringing them to faith in Christ.