How does the coming of the new religion threaten the survival of the clan in things fall apart?

He new religion, Christianity, abolished slave trade and slavery, human sacrifices and twin killing, introduced education, built hospitals and charity homes. They destroyed some level of superstition, increased human knowledge that brought about improved human welfare. Igbo traditional religion was incapable of achieving this because it was static as well as looking downwards. This was enough to convince many Igbo people to convert. Therefore, threatening the existence of the clan.