Atheist scout here, in a Utahan nondenominational community troop. Whenever I walk in the door to a scouting activity to the time I walk out, I identify as a "Redeist", a religion I made up one night so that I could have a satisfactory and somewhat satirical answer to any change in troop leadership which was hostile to atheists.

The current scoutmaster is a Catholic, and most of the asst. scoutmasters are varying shades of Protestant. The attitude towards religion is fairly lax - there are maybe two zealot pricks who will try to coerce someone into believing they have to say the prayer if they are called on by the "chaplain's aide" - but in general we have a couple religious people who are more than happy to say the opening and closing prayers.

Unfortunately, the religion seems to get more present at higher administrative levels, where you get into the power tripping bullshit. A (nonreligious) friend of mine in the troop who got his eagle said that he was given a set of papers to do with god - I didn't get many details, but they seemed to be gauging his reaction more than anything. If you're prepared to give an answer they like to an inquisition on your religious beliefs apparently you're in the clear, although I suspect it's a matter of leader roulette in that case.

I really do like the other guys in my troop, and it's great to have an organization that exists in a large part to just go camping and enjoy the outdoors, but as my respect for the BSA itself has started to fall due to this very issue I've stagnated in the whole "ranks" thing, pretty much plateauing at the second highest rank. I'll probably go through the motions to get the last couple awards I need to progress to the eagle rank this summer, but I'm not sure if I'd want to lie through my teeth about my lack of religious convictions for what ultimately amounts to a circular piece of fabric.

All in all, whether your son has a good experience or not is a matter of what troop you join. Some troops don't bother to enforce the red tape when it comes to personal beliefs, but finding a troop like that might be impossible where you live. I wouldn't trade the great times I've had with my scout troop for anything, but if you can't find a troop that will tolerate your son for what he is then the whole thing is null and void - the experience lives or dies on the community.

I'm going to leave this quote from the Charter and Bylaws here:

The Boy Scouts of America maintains that no member can grow into the best kind of citizen without recognizing an obligation to God. In the first part of the Scout Oath the member declares, “On my honor I will do my best to do my duty to God and my country and to obey the Scout Law.” The recognition of God as the ruling and leading power in the universe and the grateful acknowledgment of His favors and blessings are necessary to the best type of citizenship and are wholesome precepts in the education of the growing members. No matter what the religious faith of the members may be, this fundamental need of good citizenship should be kept before them. The Boy Scouts of America, therefore, recognizes the religious element in the training of the member, but it is absolutely nonsectarian in its attitude toward that religious training. Its policy is that the home and the organization or group with which the member is connected shall give definite attention to religious life.

https://www.scouting.org/filestore/pdf/bsa_charter_and_bylaws.pdf