The major onesDepends on the religion
By Muslim do you mean one who believes in Allah (swt), the angels, the scriptures which Allah (swt) has revealed, the messengers, the day of judgment and the qadr?If religion didn't exist, this world would be such a terrible place. Can't speak for other religions but all I can tell you is Islam has positive impacts on societies and individuals. If everyone was a Muslim, this world would be such a happy and better place.
Those who say harm pls explain?