And the way church leaders see it, there's no room for debate, even though many adherents to the faith would like to see women in the ranks.
Now, an Evanston pastor, the Rev. Bill Tkachuk, is raising the question of whether women can become deacons -- ordained ministers a step below priests.
His parish, St. Nicholas, has been kicking around the topic for months, and a longtime female member has expressed interest in becoming a deacon should the Vatican open up the option to women.
Experts said that's unlikely to happen anytime soon, given how slowly change comes to the church.
Like bishops and priests, deacons are ordained through a sacrament called Holy Orders, which is available only to men. Deacons aren't allowed to consecrate the Eucharist at mass or hear confessions, but they can preside at baptisms and weddings. They often help priests with other liturgical and administrative duties.