I have been witnessed to twice this year, once during a sale from offerup and again today at work with a coworker. The first time was super uncomfortable because it was this older man who thought I needed saving and I was just trying to buy a shelf from him. It ended up taking an hour because he spoke for so long and he also kept poking his finger super close to my chest and did make contact a few times.

Today at work a coworker I was working side by side with asked if my partner and I are the same religion and when I told her we weren't religious she was so surprised and asked me a lot of questions about what I believe(nothing) which I don't mind at all. It was harmless and she wasn't being judgemental or anything but then she talked for thirty minutes about how much she loves Jesus and how she prays and he speaks to her in her dreams and all this other stuff about atheists changing their minds and it was just so much. All I could do was make polite listening sounds and say "wow that's crazy" the whole time.

I am very shy and nonconfrontational to a fault but how can I politely tell people I don't want to be witnessed to? I don't want to be rude but I really am not going to change my mind on it and I don't really want to talk about how much someone loves Jesus for so long.

tl;dr: I'm too shy to tell people I don't want to hear about Jesus

edit: I've been reading through this entire thread and want to thank everyone for the advice. I definitely need to work on setting boundaries and I'll practice at home. This kind of thing happens a lot where I'm stuck in uncomfortable conversations where someone will break the politeness contract so I will try to remember that they're rude, not me.