The late, great Fr. Ronald Knox on the recitation of the Creed:
Since we are practically all believers, what is the sense of holding up business to remind ourselves about the things we believe?
Well, I think the most important answer is this -- you have to come to Mass to worship God, and that means worshipping God with your whole being, not just with bits of it. Worship doesn't mean merely letting your feelings go out to God, telling him how good he is and getting all worked up about your sins; doesn't mean merely letting your will go out to God, resolving that you are going to live for him and resigning yourself to all the uncomfortable things he may ask you to suffer for him.
It also means letting your intellect go out to God, telling him that he exists, that he is utterly above your comprehension, and that he has revealed himself in Jesus Christ so as to make it possible for you to comprehend him a little. That is why I have taken my text from that passage we all know, but don't always reflect on, in St. John.
The reason why I was born, our Lord tells Pilate, was--what? So as to save the world? So as to heal the sick and give sight to the blind? So as to comfort people who were unhappy? No, so as to tell the truth, so as to bear witness to the truth. That is man's first need; he is a reasonable animal, and he must know what he is and where he stands before he can sit down and be satisfied. And that is man's first duty; to think, and to think right. As part of your worship of him, God demands that you should let your intellect travel on the right lines in thinking about him. Very likely it is not much of an intellect, and shews strong signs of throwing up the sponge when it gets to recurring decimals. But it's the best intellect you've got, and it is all meant to be put at God's disposal.
--Ronald Knox, The Mass in Slow Motion, Sheed & Ward 1948, pp. 46-47.