Why are crosses smudged on people's foreheads for Ash Wednesday?

Answer 1

The ashes are produced from the burning of the palm crosses which are handed out on Palm Sunday the year before. The symbolic placing of the cross on the forehead is a reminder of baptism and a confession of belief in Jesus Christ, together with a recognition of one's own mortality. "Remember man that thou art dust and unto dust thou shalt return" are the words spoken as the ashes are applied. In the same way, baptism is symbolic of dying to sin and rising to righteousness.

Answer 2

It is their mark of ignorance. There are no such things as gods.