'Matthew 27:45-47 (also Mark 15:33-34) says: "my lord, my lord. Why have you forsaken me?"Why would "God" be asking himself why he has forgotten himself?' - I'm not even sure how this in itself leads you to believing that Jesus wasn't God. First let me remind you of what Jesus was sent to do - to die for humanity's sin that we may be considered worthy of God's kingdom through his son - "For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved." (John 3:16-17 ; KJV) and "Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness: by whose stripes ye were healed." (1 Peter 2:24 ; KJV) . For this to be achieved, God had to take on the form of man and suffer for the sins we have committed "let this mind be in you, which was also in Christ Jesus: Who, being in the form of God, thought it not robbery to be equal with God: But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross." (Philippians 2:5-8) - Take particular note of these verses: even though Jesus was 'in the form of God' (there's evidence for you right there anyway but we'll carry on), he "took upon him the form of a servant" (ie. he, God (as we have just seen) took on the form of man). The reason why this is so important is because it shows that Jesus was both God and Man meaning he had the ability to suffer like me and you. This is why the verse you referenced is not a question to God (as it may appear) the father but a cry out in pain because Jesus already knew he was going to die and thus already knew that God the Father hadn't forsaken him but rather this was what he was sent to do - "From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day." (Matthew 16:21 ; KJV).