First,religion says that it is a sin.God doesn't want you to go lusting and fucking random women if there is no love and will to build a family involved.My personal views despite religion:we are constantly bombarded with sensual stuff everywhere,we are becoming addicts to sex and sensuality.Intimacy is banalized and relationships are becoming superficial.As for segregation of state and religion,i think it is for the best that we do it.Not everyone will be a believer anyway so we can't have a political system based on principles that many people won't adhere,its not fair.I think the religious argument for a union of state and religion is that there is no better Law for humans than god's.I agree with that,but we can't have a political system like that for the reasons i already mentioned.