There are as many kinds of Jews as there are people. Some are religious and some are not, but like all other people Jews will bring assumptions to the reading of Scripture, to the concept of God and to the claims of Yeshua, Jesus.
For a Jewish person, religious or not, these assumptions are likely influenced, directly or indirectly, by the Tanakh, the Jewish Hebrew Bible. These are also the assumptions that Jesus Himself, along with His followers, held.
Do you need to know Jewish scriptures?
To understand who Yeshua is, the claims He makes about Himself and the reaction of those around Him, you need to know the Hebrew Bible. To understand any of the writings of Paul, you need to know the Tanakh. To read Hebrews, you need to be familiar with Leviticus. To ‘get’ the New Covenant, you need to be fully comprehending of the Old. To share your faith with your Jewish friend, you need to understand your Jewish scriptures.