Sexual practices of these cultures were affected by the Christian concept of male, female equality. The sexual act, according to the Church, is sacred within the context of the marital relationship that reflects a "complete" and "life-long" "mutual" "gift" "of a man and a woman", one that precludes the polygamy and concubinage common to cultures before the arrival of Christianity. The equality of men and women reflected in the Church teaching that the sexes are meant by divine design to be different and complementary, each having equal dignity and made in the image of God, was also a countercultural concept. The Church is criticized for its policies regarding women priests and birth control which are viewed by some as discriminatory towards women.