In answer to your question about Dahmer:
1. He is not in heaven:
It doesn’t matter what he believes, Dahmer was created by God to stoke the fires of Hell, and this is true even if he had led a perfect life:
Ro:9:20: Nay but, O man, who art thou that repliest against God? Shall the thing formed say to him that formed it, Why hast thou made me thus?
Ro:9:21: Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour?
Ro:9:22: What if God, willing to shew his wrath, and to make his power known, endured with much longsuffering the vessels of wrath fitted to destruction:
2. He may or may not be in heaven, only God knows because it is His decision:
Ro:9:18: Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth.
3. He is in heaven:
1 John 1:7 But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin."
I don't think there is any doubt left and I am glad to have been able to resolve this tricky theological problem.