Biblical Unitarians affirm that the Bible is the inspired Word of God and fully trustworthy in all that it teaches. The entire Biblical Unitarian theological project — especially the rejection of Trinitarian doctrine — rests on the conviction that Scripture accurately reports what the first-century church believed and practiced, and that Scripture's portrait of God and Christ is accurate rather than erroneous.

If the Bible were unreliable, the Biblical Unitarian appeal to its teaching against the Trinity would lose its force. The movement therefore has a vested interest in a high view of scriptural inspiration and reliability. Biblical Unitarians regard the Trinitarian reading of Scripture not as the result of inerrant Scripture teaching the Trinity but as the result of reading post-biblical philosophical categories back into Scripture.

The Biblical Unitarian commitment to inerrancy is functionally equivalent to that of conservative evangelical Protestantism, though the movement does not typically engage the formal inerrancy debate in the same institutional context. Scripture is trusted to accurately convey the apostles' teaching — and in the Biblical Unitarian reading, that teaching consistently presents God as one person (the Father) and Jesus as his human Messiah.