The Alteration by Kingsley Amis
Hubert Anvil is a 10 year old boy blessed with the voice of an angel. The Church hierarchy decrees that Hubert should be turned into a castrato - an alteration that could bring Hubert fame and fortune, but would also cut him off from an adult world he is curious to discover. In a dystopian world where Martin Luther never reformed and where the Holy Office's power is absolute, where will Hubert turn if he decides to defy their wishes?