John Calvin and John Wesley, of course! In reality, though, it is a case of Augustine versus Pelagius or Calvin versus Arminius. But the current title is true and just so cool.
Let us use the lens of Spiritual Warfare, but more specifically responsibility and consequences.
“For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places.”
Ephesians 6:12 (NASB)
With the outworking of life as a reflection of this invisible warfare, and an active actualization of this battle between principalities and saints, where does personal outcomes as a result of individual actions fit in?
The premise of saving grace in Reformed Theology is that it is not of us: ” For by grace you have been saved through faith; and that not of yourselves, it is the gift of God” Ephesians 2:8 (NASB). We can not save ourselves, even a little bit. So what implication does this have for living in the world after He has called us to Himself?
By virtue of our lives in creation, we are actively involved in the divine struggle. Looking at the power of the principalities involved, and our human affinity for the world of Natural Man, if we do not subscribe to the Perserverance of the Saints (the P in TULIP), we are in big trouble indeed.
Those who know that salvation is not of ourselves, but of the Lord, also know from Scripture that “My sheep hear My voice, and I know them, and they follow Me; and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand;” John 10:27-28 (NASB). Thus they can rest in the knowledge that in the ongoing battle they are safe in His arms for eternity, worldly outworking and appearances notwithstanding.
For those who take a Wesleyan view, and see a human role in salvation, and more importantly a human role in maintaining that state, there are big worries and loads of jeopardy.
We are born to sin, and for all intents and purposes can not help ourselves. We required His quickening in order to consider the promise of salvation to be other than foolishness. If any of the responsibility was or remained ours, then even once we are His how could we maintain that state? Clearly we could not, and we would be in constant danger, particularly if the end of life should approach at the wrong moment. A life of constant jeopardy is not the promised life of joy in the Lord.
Thankfully, it is all of Him alone (Solus Christus), through His Grace alone (Sola Gracia). And since His will can not be thwarted, we as believers shall preserver into Glory.
Now, does the fact that the Wesleyan does not believe this mean that he, once saved, is in any actual jeopardy? The Wesleyan would likely say yes, but the answer must of course be no.
To say yes one must assume that there is an ongoing battle in progress of the actual salvation and that the believer participates actively in its determination. The narrative of Scripture says that this is wrong.