What one biblical doctrine do you most want to understand better this year, and what will you do about it?

There are so many things I don't understand, but I have decided to spend some time focusing on the doctrine of the Trinity this year. I believe in the Trinity and I understand, at some level, the concept of God being three persons in one. I want to really understand it though, as much as it is possible this side of heaven!

This is particularly important as I spend a lot of time talking to Muslim colleagues and friends who have no understanding of this and believe that Christians worship several gods. (I have also discovered that many Muslims think the Trinity is God the Father, Jesus and Mary.)

Part of the difficulty is that the term "Trinity" is never used in the Bible although there are many references throughout both the Old and New Testament to the Trinity. I want to take proper time studying the Bible so that I can understand this doctrine, which is so central to our Christian faith, and hopefully also be in a position to better explain it to others. Friends have recommended Donald Macleod's little book, Shared Life, so I might start there.

Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit
Matthew 28:19