[ WP ] There are rituals that summon demons . Why are there no rituals that summon angels ?

I was at the fall of the Pentecostal Theocracy of Abraham. 
 Our armies surrounded the walls of the last stronghold, as they had for months. The townspeople within were growing desperate -- in the last week we had caught three times as many people trying to escape the siege as we had in the first two months. But all that was about to change, the prisoners sneered at us. Come tomorrow, they spat, the angels would be summoned to deliver them from evil. 
 That night, the church bells tolled. The torches were lit. The sentries abandoned their posts. Warily we watched as the bells rang for hours and the clouds gathered overhead. 
 I flinched when the first light shot towards the ground. More followed until the stronghold burned an unearthly white, too strong to look at. We, hardened veterans, huddled in our tents, waiting for the angels to strike us down as our prisoners whooped and yelled joyously. 
 Towards dawn, I fell asleep. I tossed and turned, running from angels in my dreams until I jolted awake with a gasp in the dim sunrise. 
 We waited. 
 By noon, the more adventurous of us scaled the fortress's walls. They unlocked the gates from the inside, and we filed in, hesitantly collecting the riches we saw. The town was empty. 
 Amidst my throbbing headache from the lack of sleep, I found myself facing the church and opened the doors. At the sudden light, the entire city, crammed into the pews, turned to face me. Screaming, I slammed the doors shut and tried as best I could to wedge them shut against the tidal wave of people that never came. 
 Silence. My headache, which I had n't noticed disappear, returned. It was n't a headache, I realized, but a low monotone chant from inside the church. 
 We sold them all as slaves. It was all we could do. The angels had delivered them from evil -- from the evil inside of them. All that remained were husks, devoid of personality, unable to make any decision or perform any action that could result in any sort of evil. 
 The children were gone. The newborns, the unbaptized, spirited away to their heaven or hell as their parents' sins were burnt out of them. Just as we burned their books, praying that no one would ever summon angels again.
