Small children, even infants, are avid learners: 

True, they cannot assimilate information like older children and cannot express well what they know, but they learn voraciously from the time they exit the womb.  Scripture even documents the case of one child who knew Christ in the womb (Luke 1:44)! 

The glory of God:

Everything in the universe displays the attributes of God (Psalm 19:1).  Everything in the universe teaches creatures something about their Creator.  However, teaching must suited to one’s level of comprehension.

The Church can teach even the youngest children something about God:

Grace Church of Sacramento offers a nursery, particularly for children under the age of 1.  Starting at age 1, there is a Sunday morning group ministry for one hour, from 9-10am.  This ministry includes worship, prayer, a short teaching time from the Bible (5 minutes) and a memory verse (5 minutes), play and cleanup.  From the earliest years, children can develop habits of ordering their thoughts and actions according to the truths of God.