why do almost all male christian singers have high voices?

They wear tight trousers.

Christian Singers Male

Not all do, of curse, but many do. Originally choir boys were castrate to keep their voices high and clear, they were known as the Castrati. There is one single recording extant that has the voice of a Castrati.

The Castrati Singers

of Italy

During the 17th and 18th centuries in Italy, some 4,000 - 5,000 boys were castrated annually for the purpose of singing alto in the church choirs. According to Melicow and Pulrang (Urology 3: 663-670, 1974), the prohibition against women singing in the church choir had its origin in the bible: "Let your women keep silence in the churches; for it is not permitted unto them to speak…" (I Corinthians 14:34). Thus, castrated men (castrati) came to sing in the choir, possessing "the chest and lungs of a man with the vocal cords of a women (Melicow and Pulrang)."

Castrati were considered to be the greatest singers of all time, dominating opera in Italy for two centuries. The last of the great Castrati singers was Allessandro Moreschi (1858-1922), whose voice was immortalized on a 1902 gramophone recording, which was later digitized and is currently available for purchase at Amazon.com.

Until Jim Morrison that was almost universally the case in Rock too. You kinda sound not into music at all.

Thats a bit of an overstatement

To praise the glory of God. High in heaven.

they don't they aren't

but you may be