First the blood wiping -- this is more of a historical rather than biblical portrayl of what occured. There is no significance biblically. What you can take from it is how much his mother was made to suffer and how brutally cruel the Romans were to the Isrealites.
The Passion of Christ is more than the cruxifiction of Jesus, it is also the story of a mother's suffering. Don't forget that Mel Gibson is Catholic and the Virgin Mother holds a very sacrid place in Catholicism.
As for is Jesus God. I could give you countless amount of historical and biblical facts to prove what you close your heart to. If you are truly interested in finding out was Jesus God there are two books I recommend.
The Jesus I never Knew by Philip Yancey
The Case for Christ by Lee Strobel
If you truly want to explore the question was Christ God these books will be a good start for you.
Here are some questions to ponder:
1) Would you brutally die a torturous death for a lie?
2) All the disciples who fled when Jesus was arrested died horrible tortureous deaths for preaching that he was the Son of God. Would cowards die painful deaths for a leader who was already dead?
3) If he is not God does his death have any meaning?
4) If he only thought he was God and went to his death due to a delusion could he really be a great Master, prophet and someone to follow? David Keresh thought he was the Son of God too.
I found some scenes puzzling, like the one where the 'creature' -which I presumed to represent Satan, was carrying a demon child. Who did the child represent?
You are right the creature is Satan. The child is a reference to Revelation, also written by John. The passages in Revelation that depict the whore of babylon and the dragon is the spiritual version of Christ's time on earth. That book is complicated and often misinterpreted so I'll leave it at that.
For those Christians who feel that the movie is an unnecessary violent portrayl of the final moments of Jesus' Life and refuse to watch it should rethink their stance. In today's world the atrocities we see on the TV whether in the news or on movies pails in comparision to what Jesus went through. Horror was a common occurance in everyday life during this time. Executions, terribly painful ones at that, were entertainment. We cannot fully comprehend what Jesus choose to endure for our sins and until we do we cannot fully appreciate our salvation.
That said I've only watched the movie once. The next day was Communion Sunday and no communion before that Sunday or since that Sunday ment so much. I finally fully understood for one emotional, spiritual, intellectual moment what it meant to eat of his body and drink of his blood. It was the most spiritual moment of my life for I finally understood what sacrifice meant.