God doesn’t take action against a person who has long history of faithfulness when he fails for the first time. For example, Satan is freely permitted to move in heaven and on earth even after many many sins he keeps on practicing. Israel as a nation was not rejected at the first instance of their disobedience. However, JW religion practices disfellowshipping and shunning at the very first act of even disbelief on any one of their vast reservoir of teachings despite decades of faithfulness.
They feel this is scriptural because this is the way Samuel dealt with Saul who was so good (reluctant to become a king when he was informed of Jehovah’s choice) and subsequently gave many victories to Israel in the difficult days of Israel’s inception period. In an emergency situation when the whole nation’s security was involved, Saul did not extend his waiting (waited for seven days) for Samuel indefinitely, but went ahead and made the sacrifice himself. This good-intentioned, extremely unselfish act of Saul was judged as disobedient by Samuel and declared his judgment: “Jehovah will choose another person to be king over Israel.” (1 Samuel 13:14) What else is needed to turn a good person into bad?
Such a hasty judgement is obviously against Jehovah’s established practice of taking action after long wait, hence is from human priestly class who wanted to safeguard their position over the ordinary people who would think ‘if king was not spared for such a small act of disrespect towards Jehovah’s appointees, how much more we.’ Without knowing this interior game of the priestly class, JW built their apostasy teaching on human ground.