Which chapter of the New Testament?

Hi Urban If I may, I believe Matthew 5 captures Jesus teachings best. Perhaps the following two chapters should also be included. Here, & particularly in chapter 5 we find perhaps the best collection of Jesus teachings & sayings in his Sermon on the Mount. This looks to be the longest straight teaching from Jesus in the whole New Testament. It is certainly one of the most quoted too. It has long been the key element of Christian ethics & for many centuries has been the guiding light for the conduct of followers of Jesus. The Beatitudes are very well known teachings of Jesus & the end of chapter 5 sums it all up very nicely, "be perfect as your Father in Heaven is perfect". All of the essentials of discipleship are contained in this sermon. The teachings therein were not strikingly new nor revolutionary originals, but would have been familiar to the listners at the time as they're comparable to Old Testament teachings. Rather, Jesus breathed life into these old teachings, elevating them to new heights. All up, the beatitudes show us a new set of ideals whose focus is love & humility rather than the old use of force & exaction.

John 3:16 is reckoned to be the Gospel in a nutshell, so it would have to be John 3. However, I would hesitate to leave an enquirer with just John 3.