Atheism will become the religion.

Humans like rituals.

In part, the answer to your question will depend on how technologically advanced and educated the initial population is. Since you mentioned their having survival gear, it’s easy to assume they may not be technologically adept.

The less advanced (technologically adept/less educated) they are, there is an increasing likelihood that there will be those that seek to put meaning to their lives through some sort of religious belief system.

The more advanced they are, the less likely they will be to develop a religious belief system.

Even then, it’s reasonable to assume that there will always be those who will develop a religious belief system, perhaps because they are less educated or less technologically adept. In each of these scenarios, above, it’s likely some religions will be philosophically based (e.g., Bhuddists) while others will develop a theist belief system. It’s even possible that, as some sci-fi writers have posited, that technology or some aspect of it (a powerful computer) could be the basis for a religion.

Why? The primary reason (hinted at above) is the desire to find meaning in their lives, to find a reason for their existence and an explanation for chance occurrences in life, both good and bad.

I wouldn't be surprised if there is always someone in a society that has "seen" something that convinces them of something supernatural. However, there is a quote from Hitch that goes: If religious instruction were not allowed until the child had attained the age of reason, we would be living in a quite different world.
Imagine a world without any religious instruction with reason and just what we know now through the sciences as a platform for resolving strange events or sightings. Unexplained things (a major gateway for theistic belief even today) would be investigated and scrutinized rather than viewed with unquestioned awe.
Individual supernatural beliefs might be sporadic but I don't think there would be groups that hold to a religion like there are today.

My first choice would be scenario A, but based on my observations of this site I'd lean more towards B. I came to this site thinking there would mostly be open minds and no cliques, boy was I wrong. Anyway, to answer the last part of your post, I see said atheist base eventually devolving into a cesspool of arguments. While I could certainly be wrong about such, over the years a good portion of my interactions with others leads me to believe human beings must find something to argue about. Again, I could be wrong about such though...

After I hear back from some of those I had messaged, I will be parting ways with this site. It was a pleasure interacting on your posts, and I wish you well Betty, do take care.

It's not unheard of for some atheists to convert to theism. I suspect that even in an atheist society some people will eventually decide there has to be something more and, over time, a certain percentage of the population would break off and form a religion. Over the span of a thousand years, I expect it would be inevitable.

A. You just don't go back to that shit once you've evolved.

I assume that atheists will be prepared for the task at hand and write the real history of the origins of their quest. Though as we know the environment and the colonists must co-operate to a degree for successful multi generational life. I've been around for 53 years and expect to do it again tomorrow in similar fashion as today here on Earth. Interesting, will you write a storyline with this scenario? I choose A, that is if all goes well for the party.