salam brother, is it haram to shop at places like salvation army thrift store? the money goes towards drug rehab centers i believe but it's a christian organization (thst helps a lot of ppl) & i was wondering if it would b haram since it might b used for preaching christianity.
Alaikumassalam wa rahmatullah,
There is no issue with it because it’s not your responsibility what a person does with the money once you buy something from them. The Prophet 
bought and borrowed things from the Jews of Medina. Buying things from Christian organizations is probably even better than buying from random people because they will likely be using the money for more principled things. And if it becomes a cause to guide people to God through Christianity, then that’s a good thing too. We should never consider converts to Christianity as competitors to Islam. We should think of them as people who went from a worse to a better state.
The same applies to people who convert to Shia Islam. We should be happy that they found God. The choice for them wasn’t between Shia and Sunni Islam, it was between being lost and being guided. Even when people convert to “Sufism lite” where they try to be spiritual without praying or abiding by Islamic law, this should be considered a blessing. They went from a worse state to a better state, and it’s God’s business if He wants to take them further.