F there is anything that God despises, it is a hard heart. The pre-captivity Jews were guilty of being so hardhearted that even their tears were insincere and self-centered. Beyond that, the Jews who endured 7 decades in Babylon weren't altogether humble in their ritualistic worship either. According to God, both their feasts and their fasts were little more than formal navel-gazing (Zechariah 7:5-6). Still, the Lord had a message for that post-exilic population, and He sent that message through Zechariah.
God reminded these people that there had been a time in the past when their forefathers had cried, but they had not been heard (Zechariah 7:13). Even so, for these relatively noble Jews, if their tears were insincere, God would not be fooled by them. God looks for truth in the inward parts (Psalm 51:6 & Zechariah 7:9). He looks for genuine generosity and compassion in our actions (Zechariah 7:10 & Luke 18:22). God looks at our heart as we perform our rituals, not at the rituals themselves (Zechariah 7:10-12). He looks for humility and contrition rather than pious exhibitions. He WILL allow us to become adamant in our rebellion, He just won't let our adamancy go unpunished.