This is a simple basic Catechism for Catholics, which begins Why are we in this world? We are in this world, that we might know God, love Him, serve Him and thereby gain Heaven. Can we do this by our own power? No; we need the assistance of Divine Grace What must we do that we might know God, love Him, serve Him and be saved? We must: 1) Believe whatsoever God has revealed; 2) Keep all the commandments we are Commanded by God to observe; 3) Make use of the means of grace which God has given to us for our salvation. How shall we learn to know these three things thoroughly ? By studying the Christian Doctrine.