The groups were originally scattered and had in common puritanical and anti-clerical tenets. A few were dualist, although the opposition of matter and spirit came to be widely accepted among the various Cathar communities. The dualistic beliefs of the Bogomils came to western Europe after the Second Crusade. The beliefs of the Cathars are known primarily through those who opposed them, and those who argued against them say that Cathars believe that matter is inherently evil and only the spiritual is good.
Salvation comes through conquering the needs of the body.
The Cathars, then, abstained from marriage and from eating any animal products. They are said to have considered children to be the work of the devil. They believed that Lucifer was Christ's older brother, who had rebelled against the Father. Satan was equally powerful and co-eternal. He could create anything except a soul.