hi Mint, a lot of Buddhists in the west, myself included, are like you, coming to the Dharma from another religious background (predominantly Christian). and a lot of us carry a deal of anger and bitter resentment towards our religious backgrounds and upbringings. i guess this is maybe natural and to a degree understandable. but it is important, as your post acknowledges, to make peace with all of that.
i only have my personal experience to share i'm afraid and i hope, at best, that it is useful and, at least, mildy interesting to read. My dad was a rector for the Church of England but quit the ministry when i was 14. My mother was, and still is, very devout. Myself, in a fit of immature adolescent rebellion, decided it was all bullshit and that alcohol and drugs was much more interesting than God and communion. As i got a little older, i became interested in other religions, inc. Buddhadharma, but never really settled down into one - just skimmed the surface reading as much as possible about all the different kinds without really going indepth into any of them. Anyhoos, to make a long and tedious story a little less long and tedious, i kept being drawn back to Buddhadharma. A few years later i was fortunate to find a sangha, good teacher and tradition i was happy in. The End.
i was still carrying that anger and resentment at my religious upbringing with me. Now, both my parents had been nothing but supportive of my decision to follow Buddhadharma - my mother even visiting the temple with me on several occasions. When my master told me i should take retreat at the Head Temple here in Fukuoka, i ummed and ahed and hesitated while both my parents encouraged me to do so. Similarly, when i was invited to live at Sanrin Soja, it was my parents who supported and encouraged me to say yes.
Shortly before i went on retreat, i remember talking to my mother about our respective faiths. i told her it was very important for me to aspire to birth in Sukhavati so that i could return and free her from the rounds of Samsara. But during retreat, realising the support and encouragement, genuine interest that she had shown towards my own path - i realised how selfish and full of shit i had been. i never treated her own path with such interest, never gave her support and encouragement, quite the opposite - i viewed it with quiet disdain. And i realised - it's not a case of me being born in Sukhavati, returning and liberating her, because all the time, she had been carrying me on her back toward the Pure Land! i was just too blinded and self absorbed to realise.
i guess if there's a point to any of this it's that i was lucky enough to know someone (in this case my mother) who was open-minded, non-judging and loving enough to accept that someone had chosen a different path, one other than Christianity. If you are lucky enough to know anyone or can find anyone like that, and talk honestly and frankly with them, it can go a long to helping make peace and shedding that anger and resentment.
wishing you the best mate