I want relics in the game. You should be able to steal or create relics. Also, "retrieve relic" should be a casus belli, similar to the pagan raids. Hmm. Not to forget, having a relic should increase your income (if put into a city), your army morale (if kept by ruler) or your piety / religious authority (if put into a church). Of course, you can also lose it if that place gets raided / you lose a battle.