From #8: Faith is our response to a world which engages us personally, to a "Thou" who calls us by name.When we pray using "thee" and "thou," we always feel so formal. I've heard people complain about certain translations of the Bible, namely the KJV, because it has so many "thee"s and "thou"s. No one speaks like that anymore.
And it is probably because no one speaks like that anymore that we've forgotten its original usage. "Thou" is actually informal. It was used in ancient times to denote familiarity, sometimes even disrespect.
So, God is a "'Thou' who calls us by name." Our relationship with God isn't supposed to be cold and formal. It's supposed to be intimate. God is our friend.
In prayer, instead of worrying about saying a memorized prayer correctly, we need to talk to God like He's our friend, like He's in the room with us.
Because God is not only a friend, He's more than a friend. He cares and loves about us more than we could ever possibly understand. He knows what is on our hearts and minds before we even tell him. But He still would like to hear it from our lips. We need to be in a relationship with Him.
And as Catholics, we have a whole host of other holy people to have a relationship with as well.