Why is walking into a Catholic church different than walking into any other building? I mean, there are a lot of really nice buildings around - art museums, lovely houses, enchanting stores and restaurants, even other houses of worship. Why is a Catholic church different?
Because when you walk into a Catholic church, you enter into eternity.
You enter into a place where time has no meaning. It simply is. It's the place where God dwells, and God is eternal, so there is no time. At least, not "time" as we humans understand it. There's no clock next to the crucifix, no timer going off to let you know that "time is up", no schedule that tells you when to come and when to go. (Yeah, I know that there is another Mass on Sunday morning, but you don't have to clear out. You can stay.)
Christ is present. No, not just "I feel warm-and-fuzzy-close-to-Jesus-when-I'm-here". He is actually present: Body, Blood, Soul and Divinity in the Tabernacle, and made Present in the Sacrifice of the Mass. As close to you there as if He were standing in front of you. You won't be any closer. And Christ, in His Divine Self, exists outside of time: He is Eternal God. You get to be there with Him, in this timeless place we call church.
It is an awesome idea that, on Sunday mornings, when you're worried about whether your son combed his hair, or if you're going to jog down the aisle just ahead (or just after) the priest, or whether you forgot to write a check out for the collection basket, that as soon as you open that door: you have entered into eternity. You are present with God. You are no longer in Sparta, or in White Plains, or in Sacramento or Paris, or in Santo Domingo. You're in an eternal space with God.
I suppose that those of us who are Catholic always "feel" a certain something when we are in a Catholic church, regardless of where it is. It feels like home. And this is part of the reason: God is there, always. A Catholic church is a step out of the mundane, the ordinary, the profane. It is Heaven on earth. And it is right down the street. Go.