They are surprised when you declare your intention to join their order. A young priest holding a sword steps forward, his hand ready to use the weapon, but before he can do anything, the man wearing the breastplate says "Stop!" and the man stops immediately, recognizing his authority.
"By the sacred rules, our church must accept"

The other priests grunt in frustration, but none dare challenge him. He says "Our dear God is merciful, but is also very strict, and you don't want any trouble with him. Please show our new sister the nuns' quarters."

"Welcome, sister, welcome to the church of the only true God"
They quickly escort you to the nuns' quarters, and the sisters offer you a collar with a golden cross.

You accept your new clothes and your chastity device, but it's a female chastity device, and they will discover you!

You can lie and say that you are a female with an "issue" that disturbs you and shows your penis, or you can try to put the device pressing your penis and trying to hide the issue.