Jesus said “Satan can’t cast out Satan” when people were accusing him of using demonic powers to help people. This was his way of showing that he is God and not some fraud with occult powers.
But there does seems to be some examples of “Satan casting out Satan” in other religions that deny the divinity of Christ and use heretical means to accomplish said tasks.
For example (s),
When a Hindu says a prayer or mantra to Hindu godswhile they are under attack by a demon and the demon goes away.
When a New ager uses tactics to cause a ghost to flee a haunted house.
When Buddha was tempted by a demon and the demon’s two daughters while he was meditating and on the brink of “enlightenment”, the demon was trying to keep Buddha from reaching “enlightenment”
The admonishment practices of Muslims work against evil spirits
How would this be possible?
If your answer is “Because Satan wants to trick them into thinking their religion is correct by acting like he is repelled by them.”…then what reason do you believe that he wouldn’t be doing that with Christians?