Have you ever wondered why people pray or what are prayers for? By prayers, I do not just mean asking God for better health or more money, I mean the actual rituals of doing it 5 times as a Muslim. You know what I am talking about, the Salats. You see, if God is All-Powerful and All-Wealthy why does he commands us to pray? Does he need our prayers?
We exercise, because it is good for our body. We read because it is good for our mind, that is assuming you are not reading gossip blogs or magazines. Read what Allah has said about the usefulness of prayers.
اتْلُ مَا أُوحِيَ إِلَيْكَ مِنَ الْكِتَابِ وَأَقِمِ الصَّلَاةَ إِنَّ الصَّلَاةَ تَنْهَى عَنِ الْفَحْشَاء وَالْمُنكَرِ وَلَذِكْرُ اللَّهِ أَكْبَرُ وَاللَّهُ يَعْلَمُ مَا تَصْنَعُونَ (29:45)
CONVEY [unto others] whatever of this divine writ has been revealed unto thee, // <![CDATA[// and be constant in prayer: for, behold, prayer restrains [man] from loathsome deeds and from all that runs counter to reason; // <![CDATA[// and remembrance of God is indeed the greatest [good]. And God knows all that you do.
So that is the purpose of prayers. To stay away from loathsome deeds. Does that mean people who pray do not commit sins, be it big or small? Well some do, and the reason why they do that while still continue to pray is that they pray wrongly. At best they do it because it is part of a ritual. And when they do it as part of a ritual, then they do not understand why they have to do it, thus, prayers will have no positive effects. If you ever wonder why it is recommended we pray Jamaah (in groups), that is because there must be one within the group who is praying for the right reason, and the promise of the prayers will cover everyone in that group including those who praying because they assume it is just a ritual exercise. But it will not have any effect if you are praying alone and thinking it is just a ritual that has to be done. Just like if we exercise wrongly we injure ourselves and if we read the wrong material our view of the world around us become distorted. But unlike physical exercises where it is possible to see when one does them wrong, or reading the wrong material, no one but God knows whether you are praying for the right or the wrong reasons. So do it right to receive what was promised by God.