A tragic, step-by-step process of a nation distancing itself from its Creator unfolds, moving from ignoring spoken warnings to a complete break in both faith and practice.
The primary approach among commentators is that the people first ignored the voices of the prophets, teachers, and guides who tried to warn and direct them [מצודת דוד, רד״ק, אבן עזרא]. Others explain this initial failure as ignoring the voice of God Himself, who commanded obedience, or disregarding a call to return to the Torah through a genuine intellectual awakening [אברבנאל, מלבי״ם, ביאור שטיינזלץ].
The downward spiral continued as the nation refused to accept correction or learn from experience [ביאור שטיינזלץ]. They failed to absorb the lessons of history, ignoring the harsh punishments that had already befallen other sinners, such as the exile of the Ten Tribes or the destruction of neighboring nations [מצודת דוד, חומת אנך, אברבנאל]. Rather than returning to God out of a healthy fear of consequences or dedicating themselves to practical commandments, the people remained completely indifferent [מלבי״ם, אברבנאל].
This indifference soon led to a deep flaw in their faith and reliance on the Creator. Because God is the active maker and renewer of the world, it is only logical to seek His help [מלבי״ם]. Yet, instead of placing their trust in Him, the nation chose to rely on its own military strength and chased after political alliances with foreign powers like Egypt [מצודת דוד, אברבנאל].
The disconnect reached its peak when the nation completely failed to draw near to God. Even though God relates to His people with close, personal care and individual guidance, the nation did not take advantage of this intimate bond to seek His assistance [מלבי״ם, מצודת דוד]. They demonstrated this lack of closeness by abandoning the study of Torah, which is the essential path to attaching oneself to God [חומת אנך]. Ultimately, they preferred the company and affection of foreign empires, such as the Romans, over any relationship with their Creator [אברבנאל].