sounds all good, and there is a little background of the cult in the OOC thread, see if you can weave that together with your concepts..
I had already dug up the OOC thread, so I wrote it with those points in mind. Here is a more fleshed out text, combining it
Posting it here, but feel free to copy any or all of it over to the OOC thread.
In the middle ages, sometime around 13th century, the families located in the mountains of western Europe, founded what would become the church of Adam and Eve. In the beginning, it was part of the Catholic Churc. Its remote location had always made it unpopular by the clergy, so it was easy for the followers of the belief to make sure their own people served at the local church.
When Luther triggered the protestant movement, the church stayed out of the religious wars tearing Europe appart. But in time, they cut the chord with the Catholic church. But they kept certain parts. A priest can not marry and form his own family, and only men can become priests. But a priest is referred to as "Father", so they are not living in celibacy; as in a way, they are a member of every family.
The idea triggering the cult, or "Church of Adam and Eve" if you will, is in large part lost to history. But it might have come from the village's isolated location, making close related the only option for partners, combined with a disrespect of the institution of marriage; the village rich man paying the priests to come up with an excuse for incest; or just a couple of bored priests philosophizing over the bible. But regardless of the reason, they started to preach at the local church that the original sin the serpent tricked Adam and Eve into was to abandon incest.
God had created just one man and one woman, wanting them to populate the Earth. The wifes of Adam's son's had to be their sisters; and if they weren't daughter's of Adam, then Adam's sons married women being their own half sisters and possible even their own daughters. God had easily have created more men and women if god was against incest.
When god flooded the Earth, he just saved one family, to yet again repopulate the Earth. Saving more families surely must even be easier for god than creating men and women.
The daughter's of Lot were never punished by god for being with their father. But there is a lot of examples in the bible of how god punish transgressions.
The evidence was clear to the local clergy. God wanted people to have incestous relations. By following the wishes of god, as god is forgiving, they might in time be allowed back into paradise instead of living in the land of Nod.
The only way to become part of the Church of Adam and Eve is to be born into it. The people of Nod is not family, so they can't fulfill gods demand for incest; and a person starting a family with someone outside the church is committing the original sin.
As the industrial age hit, families got spread over the world, but mainly the US and Europe. This required a change in how to handle things, as there otherwise easily could break their church down into several different unconnected families. The sense of the village had to remain even over the world. So while it might not be possible to just walk over and help repairing a neighbor's roof, it was possible to assist each other financially, with education, and with advice. It was also decided that each family should be encouraged to marry at least one daughter or son to a family on another continent. The latest few decades being less authoritarian and less family oriented had led to more of the church youth questioning the teaching and going their own ways; something the priests considered moving them further away from paradise.