"Both children and parents in Reformed congregations often ask, 'Why must we (or our children) memorize the catechism? If they must memorize anything at all, should they not memorize Holy Scripture instead?' These are fair questions, but they rest on dubious premises.
The first premise is that memorization is somehow out of date or a backward practice. Quite to the contrary, in most circumstances (there not being any significant developmental disabilities) memorization is a most valuable skill to teach our children and further, contrary to much modern educational theory it is exactly what they want at a certain stage of their development.
The second premise sounds pious but contains within it a sort of sugarcoated poison since it juxtaposes implicitly the theology and teaching of the church against Scripture. As a matter of fact, we understand our catechism to be a good, sound and accurate summary of the whole teaching of Scripture. As a matter of history, all heretics quote Scripture. What makes us Reformed is how we understand Scripture and this understanding is summarized in the catechism. This is, -why we have a catechism".