God is not upset that Gandhi was not a Christian, because God is not a Christian! All of God's children and their different faiths help us to realize the immensity of God.
If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse and you say that you are neutral, the mouse will not appreciate your neutrality.
For Christians, who believe they are created in the image of God, it is the Godhead, diversity in unity and the three-in-oneness of God, which we and all creation reflect.
In the Bible, we first encounter God when he sides with a bunch of slaves against a powerful Pharaoh, an act of grace freely given.
Percy Bysshe Shelley
Edmond de Goncourt