How advisable is it for someone awaiting their permanent Green Card to leave the country for a month or so.?

If she is awaiting for her green card she could apply for Advance Parole or Form I-131.She has to include a copy of her Notice of Action (NOA1) along with the form and letter explaining the reason of the trip.It could take 2 months to process and the travel document is good for one year.

If the person leaves the country, then she won't be able to come back in until she receives her green card. She hasn't even been approved yet (Her i-130 might be but not the actual immigrant status). If she leaves the country now, she'll have to wait out the green card process in her home country. She can't even come back in with a tourist visa.

My advice: wait until she receives her actual green card before she leaves the country. The baptism can most definitely wait.

depends on how she got here legally or illegally..she may have hell trying to get back home if that is they case...sometime people have to sacrifice and not go tho these ceremonies can't they have the baptism here? I would not go!

Back "home"?