What they will admit to (or else not admit, even if but to themselves) is not what matters.
What is being done (and/or not done) in way of worship due to Himself (alone) is what matters, and the Lord knows all.
There's no double-talking allowed in His realm and sight.
It's only a matter of time for any of us and all of us, to find out. We all reach our own earthly end. Sooner, or later.
It matters when non-Catholics falsely accuse us of not being monotheists.