Rob Bell is right. God did not originate from this world or Mexico or China. Therefore God is a alien.
But God exist in a profound form in every inhabitants in this universe. To love an alien is not different from loving God.
In the parable of the Good Samaritan (considered alien among Jews), Jesus picked a loving alien, an outsider, to illustrate the greatest Christian act. That is to love your neighbor(aliens included) as you love yourself.