You equated an "untruth" with a "lie". While every lie is an untruth, not every untruth is a lie.
he asked whether I personally believe that any lie is absolutely morally wrong. I never said I did. I deny it even now.

Anyway, if you look up "lie" in any dictionary, one of the meanings listed will be "a falsehood".

Untruth: it is a superior formulation of the word "lie".

"To deceive intentionally" is not a tautology.