Post History

We are concerned with being the cause of somebody else erring.  Parshat Kedoshim tells us "do not place a stumbling-block before the blind", which is interpreted to mean not only what it plainly says but also "don't be an enabler for a bad outcome".  Causing somebody else to unknowingly transgress what God wants us to do is a pretty serious "bad outcome".

In order to become a rabbi one must study halacha and the sources that inform it in depth.  Non-rabbis can also be serious scholars and I wouldn't write off a lay person who is, but most people don't know one.

As for "local", I think this is shorthand for "consult someone who will be *your* rabbi".  Pirke Avot tells us "make for yourself a rav"; this is because most questions are not so clear-cut, and individual circumstances can bear on the answer.  The rav needs to know not only the specific question but what is causing you to ask it.  For example (and I'm just making this up here; I am not a posek etc), if you ask the generic question "can I go to a church service?" the answer is generally going to be "no".  If you ask "can I go to the wedding of the sibling I've just recently reconciled with, who is marrying out, but not showing up could undo that reconciliation?", the answer might be different.  Your rav should be someone who knows you and ideally you should be having these conversations face-to-face, hence "local".