No preacher of anti-Hindu faiths should be allowed to enter Hindustan. If you Hindu see any of them, insult them. Then they will go away, and will not be able to convert Hindus.
If you are able to debate with them and able to win, then debate in public, to defame them, and/or make a video of the debate and put it on a website to defame them.
https://youtu.be/at4A0aOVqs8?t=36