1) Jesus Christ is recognized as the ultimate authority of Christianity yet he makes no mention of how the universe came into being. It is not necessary to his gospel.
2) Christianity functions quite nicely without recourse to the Old Testment.
3) The Old Testament contain things that are insulting to a true Christian faith; i.e., failure to condemn slavery, insinuates that God is an irresponsible parent, could have put a stop to the spread of evil by sterilizing Adam or Eve, failing to do so resulted in his murder of untold numbers in the flood of Noah, and tens of millions slaughtered in the past century.
Creationism seems to be an unnecessary diversion some what similar to the arguement in the dark ages as to how many angels could stand on the head of a pin. Like, who cares. Get on with it. Your religion is found in the New Testament and if you have problems with Genesis go see a Rabbi.