This is a general answer for any who would write Christian fantasy
I'm not writing a "Christian Fantasy", so there is no "Savior" or "Gospel" in my story. Yet, it is profoundly spiritual in a similar way to Tolkien's Lord of the Rings. The Bible is about so many things, wisdom, the nature of the heart, fallen nature, the inner struggles, and primarily "Who is God and what does he want with us?"
I understand that you love Jesus so much you want to tell the world in your story. If you are starting out, then my suggestion is to learn from Jesus. Jesus didn't jump in people's faces and say, "Accept me as your personal savior...or you'll go to hell..." Instead he was a real person who never compromised his values. He loved people, mingled with people, which meant he was very gentle and not pushy. Children loved him, and "sinners" hung around him.
Christian fantasy doesn't have to be "in your face" to make a point. Jesus gave his own disciples ample time to view him, listen to him, hear what he was about, before he asked, "Who do you say that I am?"
Jesus didn't try to capsulize the Gospel into a formulaic "lead me to an altar call" scenario. He used stories to illustrate the basic dynamics of the kingdom of God. "The kingdom of heaven is like... "bread"..."a mustard seed"..."when a nobleman goes away..."
Jesus used word pictures to convey the many sides of the kingdom of God. And so instead of looking at "The four spiritual laws" approach, which I think of as a sales pitch, rather than letting people see what you are about, what Jesus is about, which is really what the Gospel is about.
If you get what Jesus was doing, he wasn't using "smack you over the head with blunt 2x4" sayings. Metaphor and allegory don't have to be blunt.
I'll be honest. Most Christian fantasy that I've read has been too trite, contrived, predictable. It sounds contrary to the reality of most people's lives as portrayed in scriptures and as lived in so many places in the world- real people suffering, doubting, falling. Paul spent the second half of his life in a prison, not victorious living. In the Old Testament, Daniel and Joseph were both elevated yet for all intents and purposes they died as slaves in a foriegn land. Most of the people mentioned in the Bible had flaws, including Peter and Paul.
I'm not sure what age group you are approaching, but I think "sophisticated" is the best way to go unless your goal is to pretty much sum up the Gospel for those who already know the Gospel. The world is very sophisticated these days.
Sorry for this over-long answer. But many people already know basic Christian sayings. If you look at non-Christian and even anti-Christian websites and threads, they can repeat the basic Gospel. They don't however comprehend these things very well, God's love, God's nature, what sin is at its core. They only hear it in theory, but not in a revelation- the (Ah ha!) moment when the lightbulb goes on.
I realize why when I see flame-boards where Christians and non-Christians get into cat fights. Too many Christians scarcely know these things, so they can't explain them. They are in, as the book of Hebrews says, stuck on the "elementary principles" or Christian elementary school. Any writer that wants to do something great that touches peoples lives, I think it has to be revelatory of the greater picture.
Jesus did came to reveal his Father, which was so much more than a formula for how to win the heaven lottery. His first teaching was about heart issues, values, attitudes, priorities- the Beatitudes.