William Burkitt on 1 John 1:10

Note here, The impiety and blasphemy of those who affirm themselves to be in a state of sinless perfection: they do not only lie themselves, but intepretatively, and as much as in them is, they make God a liar, by contradicting what he has asserted in his word, that all are sinners: So that upon the whole it appears, that to affirm we have no sin, is the highest pride, the greatest deceit, the loudest lie, the prophanest blasphemy; it is to make the God of truth a liar, and to turn the truth of God into a lie, which evidences that his word is not in us.