Does the Church teach that

If a person has a habitual mortal sin addiction they should not go to confession until they are ready fully to get rid of it?

Well, how does a person have the grace to resist habitual sin if they don’t receive absolution?
By going to confession, with real remorse, one can gain the strength to not repeat these sing and also gets the benefit of counsel from their confessor.
Now, if someone is not truly remorseful…that’s different, yes.
But for someone who is genuinely trying…they shoudl frequent the Sacrament of Confession. What of they died with that mortal sin on their soul? That would be tragic.
We ave the sacraments for a reason. We need them, We need the grace.
One can have remorse, and thus be ready…whether they can resist the temptation, only they know. But the confessor can guide them.

When one goes to confession one must have a purpose of amendment, so one has to at least want to change, to see one’s sin as something bad.

We all fall, the point is to get up again afterwards.

spiritualdirection.com/2016/12/26/dangerous-habits-serious-or-mortal-sin

Peace

Never mind the extenuating circumstances - being cognizant of mortal sin, one should never avoid confession. Would that not 1) put God to the test and 2) place our soul at great risk?

Confess it and get spiritual direction.

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