Yes.
For some of us, non-monogamy (nm) can be an extension of our spiritual journey or an asset to it. NM may allow some people to express their love and/or s3xuality without limits. For others, it may be a divine right granted by their god(s) or belief system.
What does it look like?
How non-monogamy is celebrated is dependent upon the sect of beliefs being followed. Sometimes only sexual freedom or swinging is celebrated, but not necessarily polygamy or polyamory. If someone follows an organized religion like Islam, they would have to meet specific requirements to marry multiple women to access polygyny. Access to different parts of non-monogamy may be a gift bestowed by a deity/god in a set of beliefs, a form of apotheosis, or something earned. Some would say they access spiritual enlightenment through non-monogamy.
No Cults.
Spiritual journeys through non-monogamy should not be confused with cults.
Misplaced or excessive admiration, isolation, idolization of a person, and philosophical beliefs primarily led by a charismatic person, can be akin to cults, if not a cult. Access to you should be consensual, and you are the one giving out the consent. Please do not be misled.
So religion can be spiritual?
Religious people can be spiritual. Religion is a system of organized beliefs and spirituality is focused on the individual and what they believe. So yes, some religious people can be spiritual. some religious people may find that being spiritually aligned with their god(s) will grant blessings. This may be inclusive of access to non-monogamy (typically polygamy).
Group Activity - Orgies
Some spiritual people may engage in group "activities" to access spiritual enlightenment. Of course, this looks different from person to person. There may need to be a ritual, celebration, or natural event happening to do this for some. For others, there does not need to be any definitive reason why to trigger these activities.
What is gained?
Why are some people able to explore their spirituality via non-monogamy? What do they gain?
Connecting with other humans or spiritual beings allows for information or energy exchange for some.
Others may see how being fruitful gains them favor spiritually.
Some see it as a way to broaden their understanding of love and lust.
Some spiritualists use it as an opportunity to gain the skill of detaching while also maintaining empathy.
Others frame it to encourage their freedom as a person and consider it a way of life.
There are many reasons why people may use non-monogamy to deepen their spiritual experience within themselves or their religion.
Try to discern which path works best for you if it interests you.