We are talking in circles. In one sense we are sanctified, or set apart for holy use at the moment we are justified. In another we become more so as we grow in our walk.
Justification is a one time thing.
Sanctification is an ongoing process.
Both of which point toward our ultimate glorification.
Not if you take all of scripture into account.
Acts 26:18 to open their eyes, to turn them from darkness to light, and from the authority of the Adversary unto God, for their receiving forgiveness of sins, and a lot among those “having been sanctified”, by faith that is toward me. (quotations mine)
The Greek word used in Acts 26:18 is hēgiasmenois (one word) which leterally means "having been sanctified" followed by the word pistei which literally means "by faith". Therefore if we read the original Greek text we "having been sanctified by faith" in other words “are already sanctified”. There is no such thing as "progressive sanctification". Hebrews 10:14 can only mean that those become believers are "being sanctified" if we take all of scripture together. If we do not, then we must take Acts 26:1 as an error which it cannot be.
I’m truly not trying to be contentious here. I simply am trying to show that ALL of scripture speaks truth. We must take all of scripture into account to understand specific verses.