As I was reading material for my New Testament course, I came to an important realization:
Time travel to the past is impossible.
Quite a statement to make, but I can back it up.
I am a born-again Christian.
If I can travel back in time, I could conceivably travel to 404 B.C..
If I die 400 years before Christ was born, I will have died prior to Jesus' atoning death on the cross, meaning that I'll have died an unredeemed sinner.
"Once saved, always saved."
Thus, it is impossible to travel back in time.
This, of course, hinges on my initial assumption. If anyone manages to ever travel back in time, my salvation will immediately be thrown into question. Luckily, nobody will be willing to pass judgment on me, just as no Sunday school teacher holding to "Once saved, always saved" has ever been willing to flat-out state that Judas - to have betrayed Jesus - must never have been saved in the first place, despite believing that he wasn't.
[B.C.]: Christ not found [QED]: Quod erat faciendum