Religions persist in spite of modern knowledge

Yes mankind would be better off without religion, but that is not likely.  Religions have tricks to keep themselves going, and those with the best tricks last longest.  If only people could see the tricks involved in ideas like faith and loyalty when applied to myths, but once one has been indoctrinated (usually as a child), only some have the personality traits enabling them to escape, and indoctrination is a form of addiction, not easy to break from and very easy to find excuses for not wanting to break from.