SERIOUSLY...... friend..... with a nod to Matthew 18:15 ff...... and I speak generically; not specifically to the issue of annihilationism.
1. IMO, your mom needs to be
CLEAR on
EXACTLY what her pastor is teaching and believes. We need to get our facts straight. Not all students perfectly understand their teacher; not all teachers perfectly convey their subject. IMO, there needs to be a PRIVATE meeting, where your mother comes with HUMILITY and with the firm conviction that the problem may well be with her as a poor student rather than with her pastor as a heretic. ASK.... LISTEN..... and keep doing so until she entirely understands exactly what he is teaching..... and do so with respect (not to argue or debate or correct).
2. Once she COMPLETELY and ACCURATELY understands what the pastor is teaching (and that needs to to be strongly confirmed), she is permitted to disagree. But IMO this still needs to be private. She can share why she disagrees. And be willing to be corrected. But she needs to do so humbly (her pastor likely IS far better educated in these matters) and recognize that it is SHE who may be wrong.
3. IF it is CLEAR to her that her pastor is teaching heresy.... and requiring others agree with him..... he should be held accountable. If this is a denominational parish, he has a supervisor (a bishop, etc.). In this case, I would FIRST check out the denomination to see if its Statement of Doctrine includes this topic (that can be hard to determine; most denominations are extremely weak on what they teach). IF the teaching of the pastor contradicts this, she can MEET WITH the bishop and inform him of the situation. She then leaves it in the hands of the Bishop - who may or may not do anything as a result, but that is up to him not to your mother; it's how denominations work.
4. IF the parish is a non-denom, then in lieu of # 3, she needs to inform whatever entity exists for correctness in that parish (good luck.... but non-denoms have none) and inform them of the teaching of their pastor and why she believes this is wrong. In that case, she again needs to leave it to their hands.
5. If she does all the above..... and feels that the false teaching is dangerous and/or serious..... she should leave that parish. All this depends a lot on how much agreement with the parish matters there (how much is dogmatic - requiring acceptance). I left a parish and denomination (which was very, very painful to do) because integrity allowed nothing else. But I did so only AFTER long talks with my Catholic teachers, my Deacon and finally my pastor.... and only because there were a couple of things I had to accept that I did not. I did so respectfully and quietly.
MY half cent.
- Josiah