For practical purposes the words infallible and inerrant are interchangeable. When we apply them to the Bible, what we are saying is that only those who accept as from God all that Scripture proves to tell us, promise us, or require of us, can ever fully please him. Both words thus have religious as well as theological significance; their function is to impose on our handling of the Bible a procedure which expresses faith in the reality and veracity of the God who speaks to us in and through what it says and who requires us to heed every word that proceeds from his mouth. This procedure requires us not to deny, disregard, or arbitrarily relativize anything that the writers teach or to discount any of the practical implications for worship and service which their teaching carries or to cut the knot of any problem of Bible harmony, factual or theological, by allowing ourselves to assume that the writers were not necessarily consistent with themselves or with each other.
For me to confess that Scripture is infallible and inerrant is to bind myself in advance to follow the method of harmonizing and integrating all that Scripture declares, without exception, I must believe that it is from God, however little I may like it, and whatever change of present beliefs, ways, and commitments it may require, and I must actively seek to live by it.