Pope St. Piux X explains the importance of knowledge in this quote from Acerbo Nimis (his encyclical on Teaching Christian Doctrine - written in 1905):
5. We by no means wish to conclude that a perverse will and unbridled conduct may not be joined with a knowledge of religion. Would to God that facts did not too abundantly prove the contrary! But we do maintain that the will cannot be upright nor the conduct good when the mind is shrouded in the darkness of crass ignorance. A man who walks with open eyes may, indeed, turn aside from the right path, but a blind man is in much more imminent danger of wandering away. Furthermore, there is always some hope for a reform of perverse conduct so long as the light of faith is not entirely extinguished; but if lack of faith is added to depraved morality because of ignorance, the evil hardly admits of remedy, and the road to ruin lies open.It is helpful to remember that we are educating the "whole child"; especially significant are the intellect, conscience, will, memory and imagination. The teachings of the Church on this are beautiful and very helpful on a practical level. Over the next few weeks I'd like to spend some time considering each of these faculties of the soul and discussing practical (and spiritual) implications of each.