I’d say that perseverance of the saints isn’t guaranteed, since sanctification is synergistic. So the Arminian is correct that not all persevere–which is clearly seen biblically. And the Calvinist is correct that salvation cannot be lost–which is also clear biblically.
What is not clear biblically, and the point of contention, is that salvation necessitates perseverance. In fact it does not. We believe and are saved, we persevere and are rewarded.
Blasted assurance, I lost it again
I’ve been forsaken because of my sins.
Jesus has left me I could not sustain.
Now I’ll believe cause I want it again
Since sola fide is a distinct part of Reformed theology, at times RTs are very affirmative of salvation by grace through faith. But the doctrine of perseverance of the saints can have three responses. There is the Christian who hears what they say and actually hears free grace and understands the simple message even though they don’t understand all the nuances. They are satisfied that their faith works, thus they are saved.
There are also the others who hear the Lordship Salvation message inherent in Perseverance of the Saints and become saved and aren’t too introspective and actually become satisfied with what seems like quasi-assurance, a mix of objective and subjective assurance.
Then there is the third group, and these are the people who recognize the confusion of perseverance of the saints. How does it not obfuscate simple faith and works? Beliefs influence behavior, but faith is not a work. Better to see faith as the response to the truth, the persuasion that something is true. These people recognize the crystal clear message of the water of life expressed by Free Grace theologians.
Those in the first category usually agree with Free Grace but don’t see what the big deal is. Those in the second usually become antagonistic to Free Grace theology (with more Reformed education). And those in the third category love God’s simple message of Free Grace and wonder why there are people confusing the issue.