The Pope has made headlines again and again with his willingness to say what's on his mind, and to break from normal church doctrine. This time though, he's really shaking things up.

Pope Francis told a German newspaper that he's willing to consider allowing priests to marry, which goes against a 1,000 year-old rule. He said the lack of new priests was an "enormous problem" and that "viri probati could be a possibility."

Viri probati means "tested men" and refers to married men who have demonstrated outstanding faith and virtue.

The considered rule would let men who are already married be ordained, but would still prohibit ordained priests from marrying.

The church believes that priests act in the person of Christ and should therefore be celibate, but it does currently allow for some priests to marry.

Protestant pastors who convert to Catholicism are allowed to stay married and be ordained as priests.

Over the last decades there's been a dramatic decline in ordained priests. There's almost 2 times more Catholics than priests than there was in 1980. There are nearly 50,000 parishes without a resident priest.

Pope Francis has said that the lack of priests and of decreasing church attendence are among the biggest threats to the faith. He's also said in his book "On Heaven and Earth" that he was in favor of maintaining celibacy for priests.