No, FK, the Reformed version of this reads:
And if they do not God doesn't want them to persist in unbelief, they will be grafted in, for God is able to graft them in again.
(1) First, Paul here is saying (in the original) that they persist in unbelieef. The Reformed read it as "God wants them to be in unbelief." Clearly, Paul is not preaching Reformed theology (God forbid!).
(2) Second, you claim that the reason they persist in unbelief is because they were never "in" (actually, "God didn't want them to be 'in'"), yet Paul says again, indicating that they were "in," and they lost it.
Obviously, Paul is saying that it is possible to be "in" and fall away.
More Protestant myths debunked. Let's move on.
No, FK, the Reformed version of this reads: And if they do not God doesn't want them to persist in unbelief, they will be grafted in, for God is able to graft them in again.
Two different ways of saying the same thing.
(1) First, Paul here is saying (in the original) that they persist in unbelief. The Reformed read it as "God wants them to be in unbelief." Clearly, Paul is not preaching Reformed theology (God forbid!).
"Persist" is in the eye of the beholder. Is falling away for a month persisting? How about a year? What difference does it make? The Biblical teaching is that the children of God will not be allowed to fall away permanently. I don't see any problem with Paul's teaching here.
Obviously, Paul is saying that it is possible to be "in" and fall away.
That IS possible, but just not permanently.