No outside organization is likely to be the doom of the United States. However, yielding our sovereignty to globalism may well be.
And even if I accept your theory that the CFR is “dominated” by euro trash social engineers, and I grant their is a socialist tint to their “product” academically speaking, would that not leave room for alternate viewpoints among members. Not every CFR member is a globalist pig or an anti Semite.
The question remains of what would motivate an American politician to become a member of this organization, the mindset of which constituents is to be much, much more of an influence upon America than for them to be influenced by America. It may even be said that these elitist organizations exist in order to prevent America from being more influential around the world and instead, to 'bring America in' to global-think, despite it's pesky Declaration and Constitution -- and that "free, sovereign, People" idea.
Being a member of the CFR is hardly a move of American exceptionalism.
When I was in college many moons ago, their publications were the defacto standard in international position papers and business publishing. They drew and still draw from a variety of sources. There is a bias towards Globalist mentality in so much as the bulk of the academic side of the organization leans that way and they in turn are the ones who publish. Plus any modern discussion of foreign policy will immediately involve such entities as the UN, NATO, now the EU, and other international bodies. It is the reality of the world we live in. John Bolton is a prime example. He is a member, but if you examine his body of work, he is not fan of the UN or of Globalism in general, except where expedient in gaining an advantage for the US. However the hand dealt is that many international activities go through said body. Wishing it different will not make it true.
So painting a broad brush over the entire membership is a bit over simplified.
As to exceptionlism, there have been some exceptional Americans who have been members on both sides of the isle. Disagreeing on policy does not diminish true accomplishment.
One last thing, you can relax on the whole Sovereignty issue. We are an entirely different animal than Europe, as evidence by the very existence of this nation of people who left there. Is there a desire to bring in more trade and cooperation in matters of economics and security, yes, but that is good for both sides. The trick is maintaining the balance, and in the end, with conservatives who deal both in the principals we hold dear and the realities of a modern digital world we can work such things to our advantage. Otherwise we are tilting at windmills, because the Jeanie is not going back in the bottle, and the left is ready to make all your nightmares come true.