I think that most ‘catholics’ that leave the Faith do so not because they are unaware of the teachings of Jesus but are very much aware. They then do as protestants and separate Jesus from His Church, the Catholic Church and say they don’t agree with ‘Church teaching’. It is one thing to say that the Catholic Church teaching of willfully missing Mass is a mortal sin but quite another when we say it is a teaching of Jesus. It doesn’t help that we seldom hear about sin, satan and hell from the pulpit. So any evangelization of Catholics has to start at having a relationship with Jesus and His Church, the Catholic Church… because they are One and the Same. And stress that that relationship is quite different from the protestant notion of ‘me and Jesus’. It includes a Sacramental relationship especially in the Eucharist. When we say Amen to the Body, Blood, Soul and Divinity of our Lord and Savior we are saying Amen to all that His Church teaches also.