Then He said to them, “Therefore every scribe instructed concerning the kingdom of heaven is like a householder who brings out of his treasure things new and old.”
Jesus wants His students (believers) to know the Bible very well, that includes the Old and the New Testament. To understand the Old Testament, it must be viewed through the lens of the New Testament which is the fulfillment. Every time you share the gospel with someone you are trying to give them something that’s so valuable that without it, their soul will be condemned. If you do not know the scriptures then how can you open up the treasure box to distribute that which is valuable to the soul?