True there is One God but Deut 6:4 does not say anything about religions,,,,,,,,,,,,,,some of which have many gods.
I see that the many God's are our own perceptions of all the Attributes shown in this world by One God, who has come in Many Names as shown by many Mesengers.
In this day we are able to have a global vision and to appreciate we are one human race. This is the 'Day of God', promised in all scriptures. There is no excuse for us not to embrace unity. That's how I see it anyway and that is the Message of Baha'u'llah.
Regards Tony