Thank you for your in depth comment!
Regarding Advaita, you are right about the core message being that there is only One, but contrary to ACIM, there is no instance of the decision maker.
Maybe the I AM principle I mentioned, but this is never taught as an agent of free will to decide between the two different thought systems.
Of course, both thought systems are part of the illusion (as I may elaborate in the next part), but what is called "the right mind" in ACIM, is the way of undoing the egos thought system (=to cancel it out).
Yes, there is the concept of Ramana "to use a thorn to remove another thorn", but this whole issue of "to whom is the teaching speaking?" is not resolved with this...

What ACIM has done recently for me, is to bring non-duality from a 25 years exploration with many deep insights, to a daily moment to moment experience.
For me it was no enough to say, that there is no ego. What in my case had to happen, is a deep understanding of how the belief in the ego works and why "we" make the decision for it. In a way it was necessary to find out, how exactly this non-existent ego works and what it makes it seem so real.

Yes, language is tricky, but we can use it, as long as we don't believe it to be the truth. If we believe it to be truth, we fall into the trap many Advaita students do, of avoiding "I", "me" and "mine" in their expressions - thinking that this way they can show their deep understanding of the topic.

You are right, I maybe could have explained the difference in teaching between ACIM and Advaita better, but there are not many readers with such a deep insight in both as you. :) Thank you for giving me the opportunity to elaborate what I wanted to express and thank you for your compliments on my series!