From Tim staples:
he Catholic Church teaches infallibly, “extra ecclesiam nulla salus,” or, “outside the Church there is no salvation.” But as with all dogmas of the Faith, this has to be qualified and understood properly. The Catechism of the Catholic Church lays out the truth of the matter succinctly in paragraphs 846-848, but I would recommend backing up to CCC 830 for a context that will help in understanding these three essential points concerning this teaching:
1. There is no salvation apart from Christ and his One, Holy, Catholic, and Apostolic Church. Again, this is an infallible teaching and not up for debate among Catholics.
2. Those who are “invincibly” ignorant concerning the truth of #1 above will not be culpable for this lack of knowledge before God.
3. Those in the category of #2 have the real possibility of salvation even if they never come to an explicit knowledge of Christ and/or his Church.
So Christ said to go into all the world and tell them of Him so that those who were already saved had a chance to reject Him and be damned? Seriously?