I would suggest a study of the Christian doctrine of Divine Simplicity and a study of non-dualism.
If we're using the word 'God' to refer to the Ultimate, or to Reality as it is for a fundamental analysis, then it is free of all distinction and division. This is what it means to say the Universe is a Unity. This is not usually an idea agreeable to theists but the Abrahamic religions all have their mystical core and we find the idea in them even if the priests tend to prefer a more anthropomorphic conjectural view of God.
Thus while we can see this simplicity as a religious idea it is also a metaphysical theory and can be studied as such. For instance, George Spencer Brown's book Laws of Form is about mathematics and presents a calculus modeling how form arises from formless, or complexity from simplicity. The word 'God' does not appear, yet it is an argument for the simplicity of Reality. Plotinus indicates its dual-aspect nature when he calls this Ultimate a 'Simplex'.
This is a profound and difficult topic. We should be careful when trying to dimiss a view (its exponents would say discovery) common to one entire tradition of philosophical thought that nobody has yet manged to falsify. The question about love and justice is a good one but it is not an objection to anything, just something that is not easy to understand.