A Muslim knows how he came to be in this world, and why he came to be, and where he is headed after this life is over. Due to this, he is able to find inner peace and tranquility, avoiding the turmoil and empty feeling that stems from not knowing the answer to these essential questions.
This is because he knows the path that leads to Allah, and he knows with certainty that Allah created him, and that his purpose in life is to worship Allah. He also knows with certainty that he will one day stand before Allah to be held accountable for his actions in this life, and that he will be recompensed for them – with Paradise as a reward, or Hellfire as a punishment.
This knowledge permeates the heart and soul and allows a Muslim to be at ease with himself and in his interactions with the rest of mankind.