I wasn’t aware that there was any church who declared OSAS as a doctrine that must be believed for salvation.
There are many today who deny affiliation to any church, any denomination. They consider themselves saved, or born-again, and interpret the Bible for themselves. When I was away from the Church, I had folks trying to convince me that this was the way to go. I had people who lived together as man and wife, who were not married, tell me it was not a sin, because they were saved. They said that once they found Jesus as their Lord, they could no longer sin. "Have you found God?" or, "Have you found Jesus?" Were phrases individuals used a lot back then. I had a guy turn my stereo off while some early Springsteen was playing, saying, "Lies, it's all lies!" I think, looking back, he had probably been "smoking" before he got there. This was part of my experience, which I figured was a part of the times- but was in part responsible for my realization that it just wasn't for me.
With so many individual denominations, one can't really say without a lot of research, about their view of OSAS, but that was my experience of these people. After all these years, I'd say it's possible that groups of people, especially if there were so many in my little corner of the world, might feel that way.
Repent and go and sin no more is the standard