其實呢個係一個半宗教問題.God 係基督教義中基於三位一體呢個教條(Doctrine of the Trinity: the Father, the Son (incarnate as Jesus of Nazareth), and the Holy Spirit),God 並唔係一個 singular 而係一個 plural,所以用 bless 便可以.
God bless you is a request for god to bless someone, it's been shortened from "May God bless you". The "may" is understood. God blesses you is a statement that god already blessed someone.