But then, the word "transhumanism" loses all substance and arguing for or against it is just arguing a set of techniques individually. And I'm also not completely convinced by your analogy. Atheism is much easier to define with respect to reality. You can easily say someone is atheist and have a consensus around that observation, yet you can't do that with transhumanism, because it is so easy to just dodge the labeling and say your are part of another branch.
No, it doesn't lose all substance, nor do I see why you couldn't say someone is a transhumanist.
Transhumanism is a cultural and intellectual movement that believes we can, and should, improve the human condition through the use of advanced technologies.That is what it means to be a transhumanist, nothing more, nothing less.
Or, another definition:
Transhumanism is the position that it's ethical to radically improve the human condition using technology.So what is hard about this? It seems excruciatingly simple to me. This is the core of transhumanism. Anything more than this is a branch of it.
Just as the lack of belief in a god is the core of atheism and anything more is a branch of it.