I can speak from a calvinist perspective, so yes, kind of OSAS, but not quite. Perseverance of the Saints is sort of a tautology - we know we’re saved because we persevere, and if we don’t persevere, we were never saved to begin with.
So from that perspective, yes, I suppose I did believe there was sin that could take me away from God - it would just reveal that I never belonged to God in the first place. Which is actually a horridly precarious place to live in.