If there is a God then he is the same (supposing monotheism is true) But there are several concepts
of God, and many conceptionsof God. First of all you must not confuse God (if he exists) with the
idea or concept of God. They are very different. Just as the concept of a giraffe is different from a
giraffe. The giraffe is flesh and blood. The concept of a giraffe is (at least on one view) something in
the mind. A concept may exist without what it is a concept of (its object) existing. The concept of a
unicorn exists. Unicorns do not exist. We can also distinguish between concepts and conceptions
under a particular concept. There is a particular concept of God. This is the concept Jews, Christians,
and Moslems all share. It is of a transcendental God, distinct from his creation. But Judaism,
Christianity, and Islam, all have different conceptions under this same concept of God. For instance,
most Christians identify this God with Jesus Christ. No Jews do. And no Moslems do. But there are
other concepts(not conceptions) of God. There is the God of Spinoza for whom God is not
transcendental but immanent, and who is identical with Nature, his creation. This concept (remember
we are not talking of God, but the concept of God) is very different from the concept shared by Jews,
Christians, and Moslems.
Clearly, those who have different concepts and conceptions of God do not worship the same God.
Everyone is an atheist relative to all the other religions, so even if you worship a particular concept of
God, relative to all the many other religions, you are an atheist. Of course, if you worship some God
under a certain concept, you are not an atheist in that sense.