But ye turned back thereafter: Had it not been for the Grace and Mercy of Allah to you, ye had surely been among the lost.
That is, after all this, once again you failed to honour your pledge. This rebuke is addressed to the descendants of Israel living at the time of revelation of the Qur’ān, although it was their predecessors who were guilty of the violation. They were merely the followers of their forefathers rather than the leaders or originators of this error. As such, this style of address is a significant pointer: if a people emulate the wrongdoings of past generations, they will be reckoned with them as a continuation of the same history. The guilt of the forefathers will be shared by their willing followers and successors. And the history of the successors’ deviation and error will rightly be traced back to the time when its seeds were first planted in their midst.
‘You turned away after that’, that is, after all that has been mentioned above concerning your covenant with Allāh. You were witnesses to the glory of Allāh, you ratified your covenant with Him, and you were explicitly warned against the dire consequences of going back on your word. Despite this, your forefathers broke their promise, and now you, their descendants, are following the same evil course, walking in the footsteps of your forefathers of yore, having thrown your covenant to the winds.
had it not been for the grace and mercy of Allāh to you, you would surely have been among the lost
In other words, as far as your deeds are concerned you rightly deserved to be condemned and deprived of Divine grace long ago, but Allāh in His mercy did not do so, but gave you respite to this day. This, however, is the last chance you have to embrace the truth and to show gratitude to your Sustainer. You may not have yet another chance.
Islahi, Amin Ahsan. Pondering Over The Qur’an: Surah al-Fatiha and Surah al-Baqarah (Kindle Locations 5868-5882). Islamic Book Trust. Kindle Edition.