[Jim11]

#2. You've already concluded that it's dishonest to take the position due to the religious component.
How can you decide if you should take it anyway?
You need to weigh how much the small act of dishonesty matters to you. If it won't effect your performance and delivery of the material then perhaps you can just take the job and not think about it much beyond that.

#3. You just need to mentally separate what is in your control and what isn't. When I recognize the futility of thinking about other people's relationships or past relationships I tend to forget about it.

If you are the type of person that often contemplates "what if", past events, etc, then this may be difficult to stop doing. If you're not then I'm sure you'll come back to yourself and stop thinking about it.

I rarely find comparison to other people useful for anything. Only results that usually come from it are an inflated or deflated ego.

Congrats on quitting smoking. I was also between jobs a little while ago and it definitely gives you lots of time to think.