I love to read and so many books I come across have the Gospel written into them although they are not necessarily written by Christian authors. None of them are perfect examples, but read them yourself and enjoy how God’s story is written everywhere.
The Little Prince by Antoine de Saint-Exupéry
The Alchemist Paulo Coelho
Les Miserables by Victor Hugo
Here are some allegories written by Christian authors:
Redeeming Love by Francine Rivers
Narnia Series by C.S. Lewis
Lord of the Ring series by J.R.R Tolkien
Feel free to comment with books that have had this effect on you.