The beauty of being a Reformed "Christian" is that one can make up whatever he or she wants and believe it's true. It's also centered on the "feel good" self flattery which explains its appeal.
However, what Paul said grammatically is contrary to the idea that sanctification is a life-long process. According to Paul, those who accepted Christ as their savior were immediately "justified" in God's eyes, were also sanctified in the same instance.
Whether they die the next instant or live another 100 years makes no difference in their being "set aside" (i.e. sanctified), elected, chosen, saved, whatever.
Thus, the process is by necessity, grammatically expressed and otherwise, instantaneous. From the moment you are "set aside"; you are just and clean and holy in God's eyes, no matter what you do, say or think, so the conversion is instantaneous and complete, and an irrevocably accomplished fact, just as Paul expressed it grammatically.
Some people may be crazy but they are not necessarily stupid, so even those who believe with all their heart that they are saved and holy in God's eyes, know that they are not holy and that claiming to be holy in public would get them laughed at. And for a religion that is founded on me (self-flattery), that is a definite area to avoid.
No, the "beauty of being" a Protestant Christian, reformed or not, is that our faith is founded on the word of God.
Unlike the absence of faith of the self-proclaimed agnostic who believes not much of anything.
Funny that one such as yourself who says you know nothing for a fact is so certain about the error of other people's beliefs.