So you just asked who's God with to Trinitarians, so, if God be for us, who Could be against us? etc. That's how I understand this post... Not about Holy Spiritism...?
So, generally on the subject of ecumenicality. they all play nice today but formally, its about how the Pope makes the "universality" claim, the Catholic claim, he doesn't visit 'ecumenical meetings of other churches, he has observors because he can't take part because Catholics claim the only Church still. Comparatively most Churches get along that are in a struggle with this, the other Third.
I've been interested in the Presbyterians half the time prominently feature the Holy Spirit, well it highlights how Jesus was Called in his Baptism, it highlights the holy spirit led apostle Paul through Asia Minor, today Turkey, the Holy Spirit is claimed to directly be doing works. I am not sure about the 'personality' of the Holy Spirit. If it were like the other two forms of God, personality wise?