When suffering strikes, its usual purpose is to encourage a person to reflect and return to the right path. God brings hardship to awaken a person to repentance [מלבי״ם]. However, King Ahaz reacted to his troubles in the exact opposite manner. During his time of deep distress, rather than changing his ways, he chose to betray God and increase his sins even further [מצודת דוד, ביאור שטיינזלץ]. This highly unusual response was rooted in his deep-seated heresy [מלבי״ם].
The record of his life emphasizes a stubborn consistency in wrongdoing. The primary approach among commentators is that Ahaz maintained his wicked nature from his earliest days right through to the end of his life, never truly repenting. While there might have been brief moments where he hesitated or held back from certain actions because of God's word, the overall direction of his life remained firmly evil from start to finish [ביאור שטיינזלץ].