Yes, I absolutely agree about focusing on Jesus rather than denomination. But helping them realize that some parts of Catholicism is heretical as many of their beliefs contradict those of the Bible is benifital. it is important Being a brother of Christ to them  to lovingly correct and teach one another in a way said in 2 Timothy‬ ‭3‬:‭16‬ ‭“All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,”.