No, I admit I can`t really explain Galatians 1:1 in light of trinitarian doctrine. By the way, I have never said that ""God the Son raised Jesus without any help from his God and Father". The Bible clearly teaches that the authority to do this, was given to Jesus by his Father in heaven. I can try to give an explanation, but I doubt you will give it any credit: When Paul writes "Paul, an apostle—sent not from men nor by man, but by Jesus Christ and God the Father, who raised him from the dead" (by the way, why does he write "God the Father", unless he also believed that there was a "God the Son"?), his intentions are not to say anything about doctrine, but to place the reader in a state of awe: This was written at a time when christianity was in a state of flux. Were the Galatians on the verge of turning away from Pauls leadership? That could definitely be the case. If Paul had just written that he was sent by Jesus Christ (who raised himself from the dead), then this wouldn`t necessarily have had the same effect on the readers, this, at a time when christianity was still in its cradle, and none of the christians were able to agree upon what exactly Jesus was! Was he God? Man? God-man? An angel? What if there were certain members of the Galatian community that believed he was just a man. A Messiah, but not sendt directly from the heavens? Pauls point here is to emphasise the connection between God the father and Jesus Christ . Yes, he is Paul, and he has authority, given to him directly by God in heaven (an extremely powerful statement to the reader of the day) via the ressurected Son. His point is to emphasise his own God-given authority, his status as an Apostle, and his Christ-centered message. The words "Jesus Christ and God the Father, who raised him from the dead" is an anti-thesis placing the risen Christ on the side of God, and this risen Lord had directly commisioned Paul. To challenge Paul, would be to challenge the Lord that had commisioned him. And not just that, it would to also challenge God himself!
I doubt that this will impress you much, though, but this is how I would explain it. People who view the Bible as Gods word (each and every word that is in it), will never admit that there is historical development within the Bible itself, a historical development that makes the interpretation-work very, very difficult. I can accept that some people can`t swallow that. But it also sets us worlds apart, with no common ground, and that makes the discussion very difficult. Some christians can accept this continous development thruout the Bible, though, and still believe. I have to say, I admire them more.