DovidBT:
You wrote: “If someone were transgressing secular laws, e.g. committing murder or robbery, would a tolerant attitude toward them be acceptable? Why should we more lenient with halachic transgressors?”
I cannot believe you think drawing a parallel is logical at all.
Secular laws involved are social ones. They are about public safety. Getting robbers or murderers away from society is critical to the function of society. Getting involved to protect the public is praiseworthy. And halacha supports this as well.
In your label of “halachic transgressors”, we have two separate topics. There are those that בין אדם לחבירו. These are similar to the secular laws. If someone poses risk to another, then there is a reason to be intolerant, and to intervene to protect innocent victims. But there are also those areas that are בין אדם למקום. These do not involve me. HKB”H did not create me to serve as his law enforcement officer. Whether someone has failed to put on tefillin today, or ate without washing or benching, is frankly not my business. Yes, there is ערבות, and there is a mitzvah of הוכח תוכיח. If my intervening will restore an appropriate relationship between and individual and אבינו שבשמים, then there is a good reason to mix in. If not, my mitzvah is to stay out of it. The “halachic transgressor” is as much a child to HKB”H as any of us. I will never have the authority or the moral justification to block HKB”H from His child.
Finally, there is a horrible myth that dominates much of the discussion. It suggests there is a domino effect, where the OTD family member brings others down. This myth is even more emphasized in yeshivos, and is exploited as justification to expel kids all the time. The impact on another child may happen, but it is actually a rare exception. Gedolei Yisroel have been known to take a strong stand on this, and suggest retaining the close proximity and concentration of chinuch efforts on the child who is acting out, even if that means to scatter the other children to live with other family and friends. The Satmar Rov ZT”L once told a Rosh Yeshiva to throw out the other 25 talmidim, and to keep his yeshiva open for the one who was causing trouble. Rav Elyoshiv told a mother to move her other 8 children out of the home to concentrate on the one who was acting out.
The ultimate rejection of kicking a child out of the home is the nail in the spiritual coffin. Yes, I call it retzichoh. No, I did not originate this. Gedolei Yisroel said it.
Stop worrying about “halachic transgressors”. It is not your business. Just leave a path for them to return when they are ready. And if you do want to intervene, get in the business of helping bring HKB”H’s children back to him, not push them farther away. They are not less בנים למקום than you or me.