Today's Gospel features Jesus last wish from the Garden of Gethsemane - "Father I pray for them also...that they may be one as you, Father, are in me, and I am in you."
That they may be one...
This phrase is very important for us as Catholics. We take this to be Jesus asking for unity among his entire flock. Often times people take this to mean that Jesus was praying for "spiritual" unity, and that we are one, despite our differences of "religion." This suggests that our "religion" is something that really is quite trivial and ultimately can be easily transcended. This mindset ultimately believe that there is some higher plane where the "visible church" (the container of all the corruption, sin, scandal, and evil hierarchical machinery) disappears and we all join one another in a purely spiritual communion. We do well to remember, however, that as Catholics this is considered a heresy.
When we hear Jesus pray "That they may be one" we believe that he desires for us to be united in a "visible church" as well. The question then becomes which visible church is able to gather all together. The answer seems fairly clear at this point.
Pope John Paul II wrote one of his encyclicals on this subject, and the Latin title of the encyclical is "Ut Unum Sint" - "That They May Be One." I include it here as a link for anyone interested.
The document centers around the issue of how to dialogue with other faiths in order to seek unity among them so "that we may be one" some day.