I wish people would stop posting “A Tiptoe Through Tulip.” That article is like 25 years outdated. The article has a lot of truth but it unfortunately gives the impression there is a Catholic version of Tuilp when there isn’t.
Protestant theology is Pelagian and Man-centered at its foundation, whereas Catholic theology is grace alone and God-centered at its foundation. These are two hugely different foundations by which to build one’s understanding of Salvation upon. You will come up with two very different structures, even if some thing appear the same on the outside.
In the Catholic view, Adam was originally elevated by grace and needed to cooperate with grace to love God properly and maintain communion. In sinning, Adam lost that grace, and thus was no longer elevated, but rather fell down to a merely earthly level of living and interacting. Salvation was about Adam maintaining communion with God.
In the Protestant view, Adam was never elevated by grace, but rather lived on merely an earthly plane, and thus when Adam sinned there was no elevated state to fall from. This is why some honest Protestant theologians have said we should avoid speaking of Adam as “falling,” because it is a Catholic notion. In this Protestant view, salvation is not about maintaining communion with God, but rather trying to live a life without sin by one’s natural abilities if one wants to be with God in Heaven someday.
This starting picture shows that Christ’s work of Redemption will be interpreted very differently, because Christ has to rescue man from two very different scenarios. In the Catholic view, Christ comes to re-elevate us back to communion with God. In the Protestant view, Christ comes to live a life of perfect obedience in our place because we are now unable to do so.
In the Catholic view, Jesus came to restore a broken relationship. In the Protestant view, Jesus came to replace our obedience with his. This is why Protestants don’t believe salvation can be lost, because it’s not about us maintaining a relationship with God, but rather about God overlooking out disobedience and instead focusing on Jesus’ obedience instead.