If you are not Catholic, you can receive grace by reading scripture, Baptism and praying.
But by becoming Catholic, you would be receiving the fullness of the faith, receiving also the grace of Baptism (if needed), Reconciliation, Holy Eucharist and Confirmation. Catholicism is the fullness of the faith. You need sanctifying grace for salvation. Sanctifying grace is when you have no mortal (major) sin within you.
Think of it like this: Which would you rather have?
- A dinner from the convenience store or from a restaurant with all the fixings?
- A peanut butter sandwich or Thanksgiving Dinner?
- A castle with only the king in his chamber or a castle with the king, queen, all their family and beautiful hall with tapestries and gold to celebrate the feast of our king?
I’m sure you get the point. The Catholic Church has all the fixings. Other churches are wonderful and have some truths within them however; the Catholic Church has ALL of the truth. Not putting the other churches down because they do have some truths but wouldn’t you want everything?
There is nothing missing in the Catholic Church. It has the fullness that Jesus created within His church. You would be receiving the fullness of the faith directly from Jesus, Himself. Why would you want anything else?
Some people go church shopping, looking for a good pastor to preach or for that hugging warm fuzzy feeling, but there is something soooo much more to it. What about Jesus, Himself in the flesh? The Eucharist IS Jesus. You can’t find that in any other church! You can take Jesus into your heart and have a closeness and intimacy with Him that you can’t find anywhere else. This is what He meant it to be. He longs to be in you literally, not symbolically.