Parenting 101 v4 - God

When I am confronted with a difficult parenting situation, I'll put the issue out there to plumb the depths of the vast parenting knowledge of my beloved readers....Here is our fourth edition of Parenting 101.
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Walking to daycare today Lukas turned to me and said:

Daddy, what does God look like???

Quite the question, anyone know how to explain this to a 4 year old??