I think if it were a younger child, I’d continue to take them to Mass, etc., explain why you believe what you do, and enroll them in religious education. I’d also tell them that questioning, having doubts, or feeling distanced from faith is not an abnormal part of growing up.
For an adult child, yes, I believe you would need to “respect their religion” inasmuch as yelling, disowning them, or the like, not only would not help but would, I believe, be counterproductive.
Of course in either case you’d be concerned and would pray for them, and not compromise your own beliefs.
I don’t have kids but I was away from all religion for quite awhile as a young adult (was raised Baptist) and I can say that if someone (i.e., my mom) had been too stridently trying to “win me back” I would have run as fast and as far as I could.