The Word of God for Israel is and always has been the Torah, During the days of Christ – The Torah was given to be a lamp unto their feet and a light unto their path. If this lamp would’ve been bright during the earthly ministry of Christ…Israel would’ve accepted the promised King as it was written.
The Torah, the commandments, and the oracles of God were God inspired and intended to give the Jew a holy heart. A holy heart according to God’s Law…would recognize Christ as the promised Messiah.
The word backslide related to a Jew who didn’t keep the Law and Commandments. Unfortunately, backslidden Jews “did not recognize Christ when He came as their promised Messiah”.
Now He’s coming back again to Rapture His Church, bring wrath and Tribulation for seven years, and then establish His Kingdom on Earth.