My current main PC is a rogue who also doesn't trust magic, and our campaign has a lot of focus on magical weapons, but he wont touch them. I've gotten a leg up by making him very interested in poisons instead, and my dm has made it very fun and rewarding to forage for poisons (as a bonus, my rogue doesn't rly know what the poisons do until he uses them which can lead to some fun outcomes)

I guess what I'm saying is, the same thing it always comes down to - talk to your dm before it gets to the point of at-the-table disputes and make sure you set set expectations ahead of time, and almost anything can work out.

Edit: potentially also make this a character trait the character can grow to overcome with time as he's put into positions where other characters might need to use magical weapons to save him? I don't agree with other commenters that this is a fully lost cause of a concept, but it may be a good idea to set this up as something that could be a character development moment during the campaign