The victim was found with a puncture wound to her abdomen at approximately 3.15am at St Margaret's Church and taken to hospital.
A section of the church on Walgrave Road was sealed while forensic experts conducted examinations, West Midlands Police said.
Officers are appealing for witness and anyone with information is asked to contact police on 101 or Crimestoppers on 0800 555 111.
Amanuel Mebrahtu, a local resident told The Sun Online: "This is so unusual.
"The community is very nice and quiet.
"We respect each other.
"People are shocked."
There have been no arrests.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.