There are certain books that are so helpful that, if I was able, I'd put a copy in the hands of every believer I know. After a bit of reflection, I've come up with this short list of essential reading for new believers and prospective converts—a crash course in Christianity. Here it is:
Am I Really a Christian? by Mike McKinley - It's essential for the new believer or prospective convert to actually know what a Christian is. Nominal Christianity is rampant here in the American South where I live, so a book like this one is doubly important in my context.
What Is the Gospel? by Greg Gilbert - The gospel is the central message of the Christian faith, so it is vital for one to know just what it is (and what it is not).
Affirming the Apostles' Creed by J. I. Packer - This book is a very concise and readable introduction to the bare-bones basics of Christian theology.
How to Study the Bible by John MacArthur - A life of Christian discipleship is a life filled with the reading and study of God's Word. This short book is a great way to get started.
What Does God Want of Us Anyway? by Mark Dever - A lot of Bible students miss the forest for the trees. This quick overview of the whole Bible will help alleviate that problem.
What Is a Healthy Church? by Mark Dever - The Christian life is a life lived in the context of a local congregation. This book will help the new believer sort out the good from the bad.
There are plenty more that I could have added, but I think I've covered all the essentials. If you really want to bless a new believer, consider giving them these six short books.