You want a Saradomin, Zamorak or Guthix God Cape, no problem, VERY easy!
1. Craft or buy an Amulet of Glory
2. Teleport to Mage Bank (no worries nobody can attack you and you can tele away)
3. Jump in the pool
4. Follow the road and pray for the God you want the cape of
NOTE: If you want another cape just drop the one you got at the moment!