Once you are "justified", can you lapse back, fall off the ladder so to speak?
Short answer, no.
This was always an odd view in my mind. Looking at the order of salvation, if you are foreknown, predestined, and then justified; how can you lapse back? It says that God really didn't foreknown or predestined you to begin with.
You'll get the answer no by some, but the answer is yes...we can always choose to reject Christ and lose our salvation...
I'm WELS (Wisconsin Lutheran) and not sure why some protestants think once saved always saved...there is far too much scripture that warns us about this fact to be ignorant that we can slip...God knows our final destination and ultimately we can only condemn ourselves and we can only know God and his promise thru the Spirit...
Bottom line, Christ's death justified us before God...his death allows us to be found not guilty and we need to believe the promise that God will no longer see our iniquities if the Holy Spirit brings us to have faith in His Son's perfect sacrifice...if we choose to reject the Holy Spirit and in effect reject the justification of Christ's redeeming act we bring the guilty verdict back on ourselves...