'Adulterating' in the Bible

for we are not as the many, adulterating the word of God, but as of sincerity -- but as of God; in the presence of God, in Christ we do speak.

but we have renounced the things hidden because of shame, not walking in craftiness or adulterating the word of God, but by the manifestation of truth commending ourselves to every man’s conscience in the sight of God.