To be Christian means to believe in the divinity of Christ, or is baptized. Many different denominations have a wide variety of beliefs and practices, so many it would be impossible to explain the array of beliefs here.
To be Catholic means to be a member in the People of God, the Church, Jesus established while he was walking among us. While here he established a teaching authority, shepherds he would work through, to correct false teachings and be special conduits for his gifts. I like the old analogy, a train is most free on its tracks.
To be Christian is ultimately about being united to the divine and an intimate, loving, relationship. What is a relationship? Mass is described in terms of marriage, love, sacrifice. It’s so amazing. Your relationship with God is intensely personal and as such with each person its different, characterized by your personality and how God made you to communicate with Him.
Depending on in what way you want to look at Christ and his Church I would recommend a few different ways.
If you want to look up a specific topic from an academic viewpoint, I would go to www.newadvent.org, an old encyclopedia thats lapsed into public domain, and follow the trail to the original documents.
If you want to encounter the divine go to a church, get on your knees in front of the tabernacle, and just talk to God.
If you want to solid understanding of what Catholics believe and why I would recommend the Catechism of the Catholic Church, a teaching document intended to be a reference, but I find it so beautiful I just love reading it. It can be found online scborromeo.org/ccc.htm. or in print at most any bookstore.
If you want to delve into the life of Christ pick up a bible and start reading the Gospels, the books Matthew, Mark, Luke, and John.
Some people don’t really get into reading but do so much better with hearing a voice. I recommend Archbishop Fulton Sheen. He’s a blest speaker. You can find a slew of audio clips here: americancatholictruthsociety.com/articles/sheen.htm
(I really like him.)
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