Why do we say God loves you not God love you?
We say, 'God bless you', not 'God blesses you', so I see the
problem. 'God loves you' is an informative statement, similar to
'the teacher instructs us'; but 'God bless you' is a request for
God to do that, in response to some behavior on the part of the
other person. God bless you is a shortened version of May God bless
you.