In its first section the Catechism says this about God and man’s relation to Him:
God, infinitely perfect and blessed in himself, in a plan of sheer goodness freely created man to make him share in his own blessed life. For this reason, at every time and in every place, God draws close to man. He calls man to seek him, to know him, to love him with all his strength. [§1]
There are important things to point out here. First, it’s important to realize that God was under no obligation of any sort that could have compelled Him to create us. He stood to gain nothing whatsoever. He owed no debt to anyone (obviously, since prior to creation He was the only Being that existed at all), and nothing could possibly make Him more perfect or more blessed than He was. We have no claim upon God that required Him out of justice to create us. But He did create us, freely, and He did so with a purpose: so that we may “share in his own blessed life.”
And because that is His purpose in making us, He “draws close” to us. “He calls man.” He is not our enemy. He wants us to know Him and to love Him. This is why He made us, as we also saw in the opening verses of the Catechism’s prologue: “this is eternal life: that they may know You, the only true God” (John 17:3). This is man’s chief end.
Well, if that’s why we are here, then how ought we to live? If God made us in order for us to “share in His own blessed life,” then does it not make sense that we ought to live our lives with that same purpose in view? And does it not seem likely that to the extent that we lose that vision we’re going to wrongly order our lives?
This doesn’t mean that we all must become monks—as though some sort of separation from this world is the only possible way in which we can respond to our chief end. In fact that is impossible, since the monk is no less dependent upon others for his existence in this world than the rest of us are. The world is a good place, and it exists for our sake, but we have intellects and consequently a duty to govern the world in accordance with wisdom. And that requires more than mere asceticism. So we don’t all have to be monks. But whatever we do, we ought to do out of love for God and out of love for our fellow man in God. We must never lose sight of where we are going, nor why we are here. We’re on our way to God, and we ought to live like that now.