Justin continued his argument that Christians should not be punished simply because they were Christians, broadening it to talk about what Christians believe and how they behave.  In Ch. 15 he begins to tell the emperors “What Christ Taught,” quoting liberally from The Sermon on the Mount (Matthew 5), specifically the latter part.  This is written around 150 A.D., before there was agreement as to what constituted the New Testament.  He quotes quite a bit more, from other books of the Bible, as the Apology continues.  This is some of the earliest evidence of what Christians were reading and hearing.