For me, it's not about "my" Church. It's about Christ's Church. I don't think I'm so much different than most believers who believe they are in the Church. I don't think (except for purposes of writing at a forum) in terms of your Church or my Church. I just see what's been shown to me as the Church through the holy Spirit. Or: Where I found the Church.
I was a Baptist before I found where I was meant to be. I did not find the Church there. That doesn't mean it wasn't there. It means simply that I did not find it there.
No, I'm not suggesting that one needs to make concessions. If something goes against your conscience, one should not submit to it or even be a part of it. Now if a conscience feels fine with the Dispensational evangelical views, by all means one could submit.
On Marian doctrine, if looking at it from outside my communion, I do not know. My hope for others is that it doesn't matter. I hope that those things we be ignorant about will not be held against us. I'm not really sure if being taught wrong will be held against the hearer or the teacher appointed of God to teach the truth.
My advice is simple. I'll quote my departed Grandmother: "If you're gonna be a Baptist, be a good Baptist. If you're gonna be a Catholic, be a good Catholic. God looks into the heart."