Some of  my friends only study the New Testament. What can I say to them to help them see the Old Testament is important too?  

Answer: When we read the New Testament (Messianic Scriptures) we see over and over references quoting the Hebrew Scriptures/Old Testament. If we don’t know what is written in the Old Testament we can misinterpret what we are reading in the New Testament. Jesus, while on earth, taught from the Old Testament. So if it was important to Him and was the scripture He lived by it should be important to us too.