There have always been people who sensed those who have passed on from life, and they have long believed these spirits live among us. Ancient spiritualists were a product of their culture, and many of them believed in a multitude of Gods who controlled the spirit world. Today's Spiritualists believe there is only a single God, and that we are all continuously connected through this being. Their beliefs have spread, and they no longer have to hide their beliefs from the rest of the world.
Spiritualism is a modern day religion, and it has its own ordained ministers and churches. Many of these recognize there is value in other religions, and some hold on to useful ideas, concepts and traditions from long established religious institutions. Practitioners and congregants of their religion recognize no prohibition of worship in other religious belief systems, and they encourage their members to find spirituality in every part of their lives.