The same emotional appeal most religions have?
I'm not saying it has to be a major religion, just that it has to survive and by the modern day have at least a few million followers.
But part of the problem is that the Cult of Bastet (or the Cult of Athena or the Cult of Thor) ISN'T a religion, it is PART of a religion.
Judaism says 'Worship G-d because he is the CREATOR, and loves you'.
Christianity says 'Jesus died for your sins'
Buddhism says 'Follow the teachings of Buddha, and ascend to the next level, ultimately reaching Nirvana'
Bastet has none of those things. Unless you TOTALLY rip the cult apart and put it back together, you can't make her Creator of the Universe. She didn't die for our sins. Going to a heaven that is e.g. run by cats is not something I'd want, or most of us. So what appeal is she going to have.
You may think religions are random, but they most certainly are not.
Hmmm... How about if instead of trying to push Bastet, we have Bastet and Sekhmet being viewed as avatars of each other, and the worship of Sekhmet as a warrior goddess or warrior's goddess (like Ares, say, or Mithras), with Bastet being the 'fluffier' version for women to worship. So the PRIMARY appeal is to soldiers and the army. (One of Mithraism's problems being that it almost exclusively appealed to men. If we can get an equivalent that appeals to BOTH men and women, we stand a better chance.)
Would that do you?