My rule of thumb has been to capitalise when it is used together with a proper name, but not when it is used generically, as in your example. However, I have not really looked into this, which I really should.
Following @karl_lew’s very useful link to the webpage “rules for capitalizing proper nouns”, we probably find all the information we need. It seems “Venerable” should be capitalised if it serves as a title, as it may for ordained clerics in the Church of England. So are the Pali words behind “venerable”, bhante or āyasmā, to be considered as titles? My initial feeling is probably not. These are not titles in the sense of being conferred on the recipient. Also, they are not titles in the sense of being restricted to a limited group of people. It seems from the suttas that both bhante and āyasmā were used quite widely, even when lay people were speaking to each other. On the other hand, we should be careful not to impose narrow modern criteria on an ancient culture in which such criteria may not really be applicable. Perhaps the right question to ask is whether bhante and āyasmā approximate to the modern usage of titles. I am not 100% decided, but for now I think the answer is yes. Since this is so, I will retain the capital “Venerable” when it is used as a title in conjunction with a name.
When “venerable” is used generically, however, it can no longer be considered a title, and should not be capitalised. That’s how it seems to me now. Have I missed anything?
I am unsure about this. It is not clear to me what would be the limits of “religious terms”. It seems like a very broad category. The terms listed on the webpage you link to are very specific. They refer to the name of a religion, adjectives derived from such names, and God. I am not sure how far we can extrapolate from this.