The Ohr Hachayim Hakadosh writes on the Pasuk of Im Ra’isa Shor Re’echa, that if you see a Yid straying you should bring him back to his owner.
To tell you the truth, I don’t get where you are coming from. Every Yid is Mechuyav in all the Mitzvos and Kol Yisroel Areivim, so it follows that you should do what you can to bring them back to the fold. What can be a bigger Mezake Es Harabim?