In my Church we call each other "brother" and "sister". I like the reminder that we are the family of GOD. The idea of sisters being part of the Church goes way back to the book of Exodus chapter 26 verse 17. In the Hebrew I found something not noted in English versions: The boards are coupled together and called "sisters". (Strongs #269) The literal translation would go like this:
"Two pins for one board connected to its sister piece so you shall do to all the boards of the tabernacle."
Well, Sisters, woman may not be mentioned as often as men in the Bible, but if you look closely, we are the very walls holding the church together! No board stood alone in the temple, and no sister be alone either. Be strong in prayer, my sisters, stick together, and support each other. The Kingdom of God is depending on you.