Sorry for your loss.
The point of rituals like funerals is to mark important milestones and events in our lives. They are a break from the humdrum of everyday life and allow us to look at our lives from a larger perspective. A christening marks the beginning of a life and in a funeral we send off those who have left us and their lives in this world for good.
Belief in some specific deity has nothing to do with this. It goes much deeper. Rituals at the turning points of our lives are part of the universal human existence. Funerals are arranged for the sake of the family of the deceased and the wider community.