We all have to believe in something. We all have to have faith in something. It's inescapable. If you are a normally functioning human being, you have faith in something, whether you think you do or not. Even if the very idea of faith makes you laugh or cringe, you've still got it.
To be clear, I'm talking about faith here as it is defined by Merriam-Webster Online in definition 2 B (1), which is, I believe, most relevant to this conversation and which defines faith as "firm belief in something for which there is no proof."
Now, the two things I most frequently see cited by non-religious people as being opposed to faith (by which they typically mean religious faith) are science and reason. (This is, I believe, a false dichotomy -- I see no real conflict between religious faith on the one hand and science and reason on the other -- but I'll accept it for the time being.) But my argument is that even those who claim to live and see only by the lights of science and reason -- even the most hardcore -- still have faith.
They have faith precisely in science and reason. Now remember, faith here is a "firm belief in something for which there is no proof." Is it possible to prove -- prove -- that either science or reason works? Is it possible without resorting to a circular argument? Can you demonstrate that the scientific method is reliable without running more experiments? Can you defend any line of reasoning without resorting to further reasoning? Eventually you have to believe in something that can't be proven. And that's faith.
Please understand that this is not me railing against science and reason -- I love science and reason. My point is simply that we all have to have faith in something, whether we like it or not, and that having faith is not only not irrational, it's necessary.
As for me, I've chosen to put my faith not only in science and reason, but ultimately in Jesus Christ as He has revealed Himself through His Church on earth. And I'll get more into some of the reasons why I've decided to put my faith in Him a little later.