I believe that once we are saved through grace we become a new creation and cannot lose our salvation. I do not believe that there are any exceptions to this. I also believe what the Bible says with regards to taking the mark of the beast and how it will result in eternal torment, and there are also no exceptions in this regard.
So if we look at the two absolutes of eternal salvation through grace and eternal damnation by taking the mark of the beast, there surely needs to be a physical break between these two requirements to ensure that they can both be met without contradiction. And by my understanding, that break must be the Rapture. Does this make sense, and can this be used as proof that the Rapture needs to occur before the Tribulation?
Yes, this is one of a long list of things we can use in support of a pre-tribulation rapture. If you read further, in Rev. 14:12 John said the dilemma facing believers when the requirement to take the mark appears must be met with “patient endurance on the part of the saints who obey God’s commandments and remain faithful to Jesus.”
This proves that believers who will be subjected to the mark are not part of the church. We are saved by grace alone and our salvation is guaranteed from the moment we believe (Ephesians 1:13-14, 2:8-9). Tribulation believers will have to obey the commandments and remain faithful to Jesus in order to keep their salvation. Rev. 14:13 says they must do this even to the point of death. This implies that if they don’t sacrifice their lives rather than take the mark, they’ll be lost forever. Their salvation is not guaranteed like ours is.