What central idea that erasmus strived to achieve is implicit in this quotation? "only a very few can be learned, but all can be christian, all can be devout, and—i shall boldly add—all can be theologians."—erasmus

The answer is: To promote the benefits of the printing revolution

Explanation:

Desiderius Erasmus Roterodamusenjoyed the sobriquet "Prince of the Humanists", and has been called "the crowning glory of the Christian humanists".Using humanist techniques for working on texts, he prepared important new Latin and Greek editions of the New Testament, which raised questions that would be influential in the Protestant Reformation and Catholic Counter-Reformation. He also wrote On Free Will,In Praise of Folly, Handbook of a Christian Knight, On Civility in Children, Copia: Foundations of the Abundant Style, Julius Exclusus, and many other works.

Here he calls for the spread of the knowledge about Christ through printing books which would be availabe to all - all can be theologians.