I devised a method some years ago, but found no interest. There are free programs (my favorite is Audacity) that allow you to master music one track at a time. An upgrade is to buy a portable recording studio for $500 which has physical buttons and better hookups - files can be transferred to computer and converted to mp3). I will describe the Audacity method, and you can get back with whatever questions.
Everyone in the group downloads Audacity or a similar program, and makes sure their computer audio will handle their instrument or voice input. Whoever writes the song prepares a lead track, or more than one, if you wish to keep certain parts separate. Like, you might prepare a guitar track and a singer track. It is not necessary that the tracks be perfect, since they can always be erased and replaced later. But it is essential that your timing and your harmony be set before you start the next phase.
Next, simply mix the tracks to an mp3 file and e-mail it to the next person to add a part. That person opens your file in Audacity, and adds his part, listening and playing along. When satisfied, he mails you his part, and you mix them, and send the new file as mp3 to person 3. Then repeat the process, each adding as they go along.
Variations are possible, of course, and it is part of "creative control" to decide who adds first and just how things are mixed. To me, that belongs to the composer of the original song, but each can do as he wishes.
When you are done, you have an mp3 file, suitable for adding pictures and lyrics to and uploading to youtube, or wherever.
You can do better work if you save files as wav files, but normal e-mail will not carry such a large file, so you will need to start a website to transfer files over. Or maybe by now Facebook will allow for such big file transfers.
There are programs like jitsi that allow for a few people to jam together online, but the speed of light limits them to a few hundred miles distance and only three or four musicians at the most. When we at JCIC researched this three years ago, there were several initiatives in the works, but I have not checked recently.
I'm too old to care about creating Christian punk personally, but I do administer an online 24/7 Christian music stream station (offline temporarily for maintenance) called
www.jcic.us, and would be glad to add anything you compose to the random playback program.
