-Why sometimes does God not answer our prayers or worship?

God sometimes does not answer the prayers of believers for eight reasons: Amir Mu'minan,Ali (as) in response to the person who complained about the non-acceptance of his prayers and requests in God's court  said:

In response to this question, Imam Ali (AS) said: Because your hearts have committed eight betrayals:[1]

1. You all knew God but did not fulfill His right as it is obligatory; Therefore, your knowledge is not enough for you.
2. You all believed in the prophet but disagreed with his Sunnah, so what is the benefit of your faith?
3. You all read the Quran but did not act according to its verses.
4. You all said you were afraid of hellfire, but at any time you made your bodies ready for punishment with your sins.
5. You all expressed your desire for heaven, but you did something that kept you away from heaven.
6. You all used God's blessings and virtues but did not thank him.
7. God ordered you all to be enemies with Satan, you were hostile to him with your tongue, but you did not oppose him in action.
8. You put people's faults in front of your eyes, but you left your faults behind.

[1] -لِأَنَّ قُلُوبَكُمْ خَانَتْ بِثَمَانِ خِصَال
Bihar al-Anwar, vol. 93, p. 376, h 17