Yours is a bad example. Jesus said that the old law was still valid, which means that in fact you have to study the entire OT to get the full message. He just left it to the reader as an exercise
(Disclaimer: not a Christian. Constantly amazed at people who have faith)
Unfortunately if you don’t believe in Christianity there is no book or philosopher that has told the whole “truth” about the universe, so any new kid on the block might indeed have many things to say