The actual idea of once saved always saved is if you are actually saved, which is different from professing Christ, a person is always saved and cannot lose salvation. As far as persevering we have two issues, a person may backslide or get sidetracked such that they produce little or no fruit, but still in their heart of hearts belief Jesus is their savior and they love Him. OTOH, we could know professing Christians who teach and engage in public prayer and so forth, but are simply whitewashed hypocrites who give lip service to the Lord. These face Matthew chapter 7.
But note Christ's words, I never knew you. He did not say, I knew you once, but I lost you. The real problem is Arminians think if they profess Christ, they are "automatically saved" when scripture says God saves us monergistically, He credits our faith as righteousness, or not, and then places us in Christ, we do not put ourselves in Christ.
This is a very good post, Van.
Thank you!