The Mekhilta offers another example of a name diminished by moral failure: Yonadav, originally called Yehonadav. The difference is a single element — the divine syllable "Yeho," derived from God's name, which was stripped from his name after "that deed."
In the beginning, Yehonadav bore a name that carried God's presence within it. The prefix "Yeho" is a theophoric element — a fragment of the divine name embedded in a human one, signaling that the bearer walked in close relationship with God. Yehonadav's very name declared his connection to heaven.
But then came "that deed." The Mekhilta alludes to the verse in (2 Chronicles 20:37): "When you befriended Achazyahu" — a wicked king. Yehonadav allied himself with a ruler whose actions were corrupt, and the association cost him the divine syllable in his name. He became simply Yonadav. God's name was withdrawn from his.
From this, the sages derived a broader principle: "Let one not befriend an evildoer, even to draw him close to Torah." The reasoning is striking. Even if your intention is good — even if you befriend a wicked person specifically to influence them toward righteousness — the association itself carries spiritual danger. The Mekhilta does not say the effort is forbidden, but the risk is real. You may set out to elevate the evildoer, but you may find that the evildoer diminishes you instead. Yehonadav presumably had good reasons for his alliance. He lost part of his name anyway.