Although the foundation of every religion proclaims there is one God, the folowers of most faiths have come to believe that their God is unique and different from others... a sense of separation. Even though different religions may emphasise an aspect of God, this does not diminish the truth that God is One - and should not be a source of division between faiths.
Instead, our belief in God informs us that God pervades all boundaries that we have formed and that all people and all things are of one essence.
God is One
God is the God hidden in all things, all-pervading, the Self within all things, watching over all worlds, dwelling in all beings, the witness, the perceiver. - Hinduism
There is one God of all, that is above all and through all and in all. - Christianity
There is but one God whose name is true. God is the creator, immortal, unborn, self-existant. - Sikkism
All this is God. God is all there is - Sufism
God, in truth, hath in eternity been one in essence, one in attributes, one in works. - Baha'l