I’m surprised a deacon teaching either a high school or a RCIA class would throw something like that out there. No, non Catholics do not automatically go to hell.
Historically, and spiritually, salvation has flowed through the Catholic Church since the time of Christ, even to those who identify as “non-Catholic.” The Church is the visible New Covenant between God and man. Christianity would not have been kept alive, intact, and capable of being handed down if it was not for the efforts of the Church through the Dark Ages, for example.
I’ve found it helpful to think of the Church as a huge conduit. There may be a lot of pipes flowing off that conduit, but they get at least some of what is flowing through the big conduit. Or even a banquet. There might be an hors d’oeurve station and a salad bar at that banquet. You could stay alive on the salad and the munchies. But you wouldn’t get the roast, the turkey, and the lobster newberg. Sorry for the mundane analogies, which fall quite a bit short of what is really going on spiritually, but you get the idea.
The Catechism itself teaches that while salvation is through the Church, this is not the ONLY means of salvation: In ways known only to God, even pagans and atheists of good will might in fact be saved. See the above posters.
After all, God is God, and will save whomever He wants. However, they would not have the fullness of faith (and consequently, the fullness of joy) that comes from the True Faith. How could they? They wouldn’t have the knowledge base, the practices of prayer and meditation, or the Sacraments to really bolster their relationship with God.
If you haven’t already done so, get yourself a copy of the catechism (it’s available online at the USCCB, if you want to read it on the computer,) or in paperback form. It’s hefty and intellectual, but not at all difficult to read, assuming one can read at a high school level. It’s made for adults. It takes some getting used to. But, let me tell you this: As a lifelong Catholic, whose catechesis pretty much ended with the Baltimore Catechism (question and answer format,) and Confirmation, I’m always surprised when I dig into it. No, I can’t quote it paragraph by paragraph. But I’m really enjoying getting into it. I think it should be “required reading” for any intelligent adult Catholic who wants to learn more about their faith, and how to put it into action.