Why were the Jews mad at Jesus for calling God His Father if the Old Testament portrayed God as Israel's Father?

**John 5:18 NASB95** For this reason therefore the Jews were seeking all the more to kill Him, because He not only was breaking the Sabbath, **but also was calling God His own Father**, making Himself equal with God. **Isaiah 64:8 NASB95** But now, O Lord, **You are our Father**, We are the clay, and You our potter; And all of us are the work of Your hand. Other verses that show God as Father in the OT are: Deut. 32:6, Psalm 82:6, 89:26, Isaiah 63:16, Jeremiah 3:4, 19, Malachi 1:6, 2:10, etc... If this was a semi-common theme in the OT, why were the Jews so upset when Jesus called God Father?