Guess what! This will be hard to believe, but OSAS isn't a Calvinist thought. It is a twisting of Calvinist thought way back when by folks who don't like Calvinism.
So, don't blame OSAS on us.
Now, can't say I totally get what is and isn't Calvinist, and, frankly, I stink at Calvinism, because I'm too lazy to take time to figure out all the beliefs of what I'm supposed to believe just because I'm a Calvinist, so don't count me on the authority of what Calvinists believe, but here is my belief on OSAS.
I kind of do believe that, but one really important aspect is missing from that assumption. It is assumed that everyone who thinks they are permanently saved are saved in the first place. Not necessarily. Some were growing on rocky soil.
So, my belief is IF you are saved, it is permanent. The bigger question is, "Are you truly saved?" And that one takes a long time to answer.
If you don't get that part, don't worry about it. But please understand OSAS isn't Calvinism. It's anger toward Calvinists.
Kind of like a pro-abortion person saying, "You don't have say over my body."
That's a strawman argument to avoid the real issue! Assuming you are pro-life, doesn't it just bug you to death when people say you believe such-and-such, just because you're pro-life? And what they say you believe has nothing to do with what you really believe, and has absolutely nothing to do with the abortion debate?
Yeah, same feeling Calvinists have when people assume what we believe from false information. And I'm not saying you're the one giving the false info. But you are believing it, just because someone told you that. It's just not true. Partly true, but not the whole story.