Prevenient grace is that grace which God gives a person prior to their conversion. Prevenient simply means "preceding." Prevenient grace is a key distinctive of classical Wesleyan-Arminian theology. Opponents of this doctrine charge that it is unbiblical because the term or idea of prevenient grace does not appear in scripture. I grant that the term does not appear in scripture, but this doesn't mean that it is unbiblical. "Trinity" doesn't appear in scripture either, but it is a distinct and unique test of historic Christian orthodoxy. I do not grant that the concept or idea of prevenient grace is absent from scripture. It appears in John 6:44 where Jesus says, "No one can come to me unless drawn by the Father who sent me." The concept of preceding grace appears also in Acts 2. Peter had just preached his Pentecost sermon when Luke tells us that, "when they heard this, they were cut to the heart and said to Peter and the other apostles, 'Brothers, what should we do?'" (37). To say that they "were cut to the heart" is to say they came under divine conviction for their sins against Jesus in handing him over to the Romans. This is clearly prior to their conversion because Peter answers their question saying, "Repent, and be baptized every one of you in the name of Jesus Christ so that your sins may be forgiven; and you will receive the Holy Spirit" (2:38). They had not yet received the Holy Spirit so they had not yet been born again, but they had come under conviction and were being drawn to seek reconciliation with God. This is clearly grace which precedes conversion. Thus, Roger Olson can say that prevenient grace, "is the powerful but resistible drawing of God," which may not be a biblical term, "but it is a biblical concept assumed everywhere in scripture" (Arminian Theology, IVP, 2006, p. 159).
The concept of prevenient or preceding grace may also appear in some early non-canonical Christian literature. The Didache (or "Teaching") is a document from the first or second century which provides insight into a variety of early Christian ideas and practices. It isn't scripture, of course; however, it is quite telling as to the belief and praxis of the early church. In giving instruction regarding fairness towards household slaves, the author says, "for he comes not to call men with respect of persons, but those whom the Spirit has prepared" (5:10). We must be careful not to read too much into this brief statement. But it does seem to affirm a belief that God's Spirit goes to work to prepare people for conversion prior to their hearing the call of God. The objection might be raised that this "call" is something subsequent to conversion because the slaves are said to, "hope in the same God" (5:10). This objection is not necessarily the proper reading though. The statement regarding God's call is substantiating the earlier statement that God is over both master and slave (5:10). Thus, the exhortation to fairness may be grounded in the principle that God calls and saves both free and slave with no thought of their social status. If so, then the calling is subsequent to the preparing work of the Spirit. We may have here an early non-canonical witness to the concept of prevenient or preceding grace.