The devil exists to do God's dirty work, to be hated, loathed and despised. To be the bad cop. Every satan does is allowed by God, therefore God wishes it to be so. He just can't do it himself or people will see he is malevolent.
So could this be another interpretation of the characters?
- Yes. Seems about right. God split his personality so we don't all hate/blame him.Vote A
- Other / I'm not christian / Isn't two faces too many...Vote B
- No. They are separate characters which can't be merged. God is only three faced.Vote C
Don't interpret it literally - by trinity in four parts I mean actually a cosmic foursome rather than a threesome held together by that magic god juice.