When reading and studying scripture sometimes we don't always see the whole meaning behind events that happened. Some of us may prefer to just read the New Testament in our Bibles and we may even view the Old Testament (Tanakh) as a history book which is irrelevant for today.
Unfortunately this way of thinking is very common and completely wrong. YaHuWaH does not change. His Word does not change. From the beginning of time He had a plan. The plan of salvation through His son Yahushua, as shown throughout the Old and the New Testament. The Old Testament is a type and shadow of the New testament and things to come. Many books in the Old Testament (Tanakh) prophecy the Messiah's birth, death and resurrection. If we don't read the Old Testament, we will miss so much truth and amazing revelations. The term 'Old Testament' was first coined by the Roman Marcion who was a staunch disciple of the false apostle Saul/Paul.