By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles? (Mt. 7:16)
You can find blackberries amount thorns.
It's fine if the preacher wants to call Obama down on his actions and say he's not acting like a Christian or even that he is acting like a Muslim.
But last time I checked, Christians, myself included, are not a perfect people who never sin, who are absolutely correct in every doctrinal belief and who always love perfectly.
And as an example, I offer the blasting of the church for still needing milk instead of meat and Jesus finding fault with the 7 churches in Revelations.
It's possible for Obama to be a Christian and have a wrong belief about government's role with regard to abortion.