Since you have conceded the issue by your inability to post Church teaching to back your innovative position that grace vanishes without grave sin once one reaches the age of reason (or conversely, show Church teaching explaining how the justified are nevertheless damned), I'm happy to follow you into this other discussion:
Please explain how an Orthodox baptized infant who reaches the age of reason can be described as being "without explicit belief in anything." If your response is going to be, "We aren't talking about Orthodox, but about atheists," then you are willfully admitting you refuse to consider the scenario I set up at the beginning of this thread (i.e., sensing the weakness of your position, you desire to change my situational criteria, by moving the discussion from Orthodox to atheists).
Father Mueller was cited saying the exact same thing I did. You have no understanding of what a virtue or a habit is. I've also shown that this conclusion follows from Church teaching that for adults explicit faith is necessary in order to have supernatural faith and supernatural virtue, and you STILL haven't addressed that. Instead of bloviating that your conclusion is true unless we can cite Church teaching to the contrary, why don't you cite Church teaching to support your position. I'll be waiting.
I wasn't talking initially about an Orthodox-baptized infant, but was testing the principle based on the case of an atheist. With your false principles, you would have to conclude that an adult who has reached the age of reason as an atheist, and yet has committed no actual grave sin, due to his being invincibly ignorant, can be saved. But that's contrary to Church teaching. Nice try changing the subject back to the Orthodox. But then Father Mueller explains this too, but you completely ignore it. You can only make an act of faith with the proper motive of faith, i.e., based on the authority of the Church teaching. So those who reject that authority would not be able to make the act of faith, just like an atheist couldn't.
But stop changing the subject to the Orthodox-baptized infant and answer the question already about the one who grows up to be an atheist. That is crucial to whether your principles are valid or not. And you know it. But in your intellectual dishonesty you refuse to answer the question because you realize that it's fatal to your position or else you'd have to assert that atheists can be saved without explicit faith in anything.