Comment: Leggo my ergo.

(See in situ)

Leggo my ergo.

When faced with someone who holds two seemingly incongruent positions, you merely need to point this out, not name the logical flaw. This is especially effective in a situation where some fallacy of ambiguity may be present. You don't want to be led into presenting a false dilemma.

You: "If it is truly only the heart that matters, why must one resort to coerced obedience?" Based on the context provided, this is all you need to say.

It seems as though your debaters believe that coerced obedience does not imply they care less about the heart. You need to investigate this and understand their argument for it.

For example,
Them: "In fact, what if coerced obedience functions as an expedient wisdom method which plays an important role in shepherding the heart? Thus, only one who does not care about the heart would neglect such a tool."

I think your problem should be resolved through greater understanding of each position rather than searching for the appropriate Latin phrase.