The religious beliefs of Sinnsreachd are inseparable from the culture, but they deserve a good, solid look on their own merits as well. While descended, directly and indirectly in varying ways, from the original pre-Christian faith of the Gael, it is not the result of secret family traditions of hidden ?druid cults? or other such nonsense. Neither is it an attempt to reconstruct the faith of our ancestors as they followed, for such would be virtually impossible without the aid of a time machine. We simply do not know every last detail of our ancestors? faith and thus have to work from the core parts that survive in recorded lore and customary traditions. Much survived, enough to build from and reclaim our faith, but it is in a modern incarnation and not a direct continuation of that of our ancestors. It could be likened to the differences between ancient and modern Judaism- the same faith, praying to the same god, with most of the same core cultural and social elements, but also changed by time, loss and recovery or replacement of knowledge, and an expansion of scientific and celestial knowledge.
Because it is a modern incarnation of a pre-Christian religion, and not an unbroken linear tradition, some external observers label Sinnsreachd a "neopagan" religion. However, that term is highly inaccurate due to its associations with purely modern syncretic religions such as Wicca, which have nothing in common with Sinnsreachd ideology or theology. We simply prefer to be called Sinsearaithe (Sinsearaí sing.), and our faith Sinnsreachd. Nor are we fully a Reconstructionist religion, either. Our faith is a living, breathing entity in the modern world, not a well-intentioned, yet anachronistic, attempt to recreate the ancient beliefs of our ancestors as they were two millennia ago. Sinnsreachd is for today, for our people now, and embraces modern scientific and cosmological understandings of existence. We understand and accept that the Sun is a burning ball of plasma fed by a hydrogen-to-helium reaction, and not the giant flaming chariot wheel of a deity. However, the core ethics, morals, doctrine, and customs of our people are by and large timeless, and neither require us to live in an Iron-Age mindset nor to shirk an expanded and enlightened understanding of the cosmos. In fact, quantum physics and our expanded understanding of things such as non-corporeal intelligence, the multiverse, string theory, etc. are all complimentary to our beliefs in many ways. We do not need to cast aside science and modernity in order to practice our faith, but instead mold our understanding and practice of such things through the filter of what we believe.
The basics of the Sinnsreachd faith are universal, but many of the minor details may differ from tuath to tuath. These basics include veneration of the Gods of the Tuatha de Dannan- particularly the core deities Nuada, Lugh, an Mórríghan, Dana/Danú, Goibhniu, Manannan Mac Lír, Dian Cecht, an Dagda, Bríd (a.k.a. Brighid), Macha, and Bóann. Other universal aspects of the Sinnsreachd faith are the celebration of the four fire festivals- Samhain (the celebration of the end of one year and beginning of the next, and the beginning of the dark or winter half of the year) at the beginning of November, Imbolc (the festival of Bríd and the celebration of the coming spring) at the beginning of February, Bealtaine (the celebration of the summer and the beginning of the light half of the year), and Lughnasadh (the festival of Lugh and the celebration of the harvest). These festivals involve feasts and tribal celebrations, and different religious practices depending on the festival. Sinnsreachd also has a fairly universal a code of ethics and morals spelled out in various poems called Triads, primarily focused on honor, integrity and hospitality in both religious and cultural practices.
Theologically, Sinsearaithe have strong beliefs in both an afterlife- called Tír na nÓg- and reincarnation, as well as veneration of ancestor-spirits, and recognition of the spirits of the three realms considered sacred by Sinnsreachd- land, sea, and sky. Probably one of the strongest unifying theological beliefs of the Sinsearaithe is that of a pact or covenant between our ancestors and our Gods. The Sinsearaithe believe that the indigenous culture and beliefs of the Gaelic people are sacral, taught to our ancestors by our Gods as the proper way of living. To us, the tuath represents the core of this sacred way of life, and it is paramount that it be followed. Our belief is that the foreign cultural and religious influences that have overwhelmed mainstream Gaelic culture are unacceptable to follow, and represent a breaking of the pact established between Éiriu and the Milesians, a pact we are beholden to uphold. We believe that to maintain our end of the pact we must adhere to and follow the core of our ancestral culture, society, traditions, and beliefs as a way of life. In exchange for this, should we succeed in rebuilding our people and proving our worth and dedication, we will be granted a union with the land and prosperity. It is our belief that some day, many generations down the road after we have rebuilt our people and our way of life into a proper heir to that of our ancestors, we will again have a sovereign homeland in which the teachings of our Gods and Ancestors are honored.