I have an acquaintance and sometime client who loves to run pagan, New Age, and "interfaith" conferences. If given the chance, he will organize one at any time. I've been to a number of the conferences, especially back in what seems now to be the balmy and peaceful 1980s. The management would give me an art table to show my work rather than paying me real money for the logo and T shirt and program design. Sometimes this worked out, mostly not.
In the world of interfaith conferences, usually a conference is secretly organized by one of the faiths with the intent of converting the others. Other conferences are really Pagan or New Age gatherings with a handful of friendly, usually esoteric-minded Christians and Jews. Most mainstream religions will not share space with Pagans and New Age believers, even now. And good luck finding a mainstream Muslim to participate; the only Islamic presence is usually a Sufi of one sort or another, often not really Muslim at all.
Now in this time of heightened strife I don't see much of this cooperation. My logo design above is wan and hopeful compared to the militancy and aggression of most religions. You can see my attempt to "bridge" the distance between the hard-edged modern City of Rationalism and the fanciful Asian-looking City of Faith.
Original design was black ink and computer-printed lettering on illustration board, 9" x 9", September 1994.