He wanted to prove to him that the war he was fighting was a war for justice and righteousness. It was not a war for territory, money or property, but was one to uphold the principles of Dharma. If Arjuna did not fight the war, it would send wrong messages to posterity.
The first message: Arjuna the great warrior became a coward and quit the war right at the last moment when he saw that the opposing army was stronger and bigger than his.
The second message: Evil triumphs over good.
If Arjuna did not fight, the Kauravas would win and continue to rule the kingdom. Further, even though war is evil and results in death, sometimes it is necessary. Just as one has to do surgery to cut out a cancerous part of one’s body, similarly when people in this world are unholy or wicked, then they need to be eliminated. If they do not listen to reason then one may have to even kill them or eliminate them from the society.
Arjuna had several other doubts and questions and the discussion in the Bhagavad Geeta then turns not only towards his duty but towards other aspects of life like how one should live in this world, other paths of worship etc. A detailed description of the Lord Himself and His qualities are found in the Geeta. The path of Self-realization is also expounded. The Geeta is really the most important text in Hindu religion since it teaches us how to live in this world, how to become better person and how to obtain a higher status not only in a secular way but also in a spiritual way. Ultimately the Geeta also shows us the path to Self realization or realization of the Supreme. It contains the essence of all the Upanishads. We have several Upanishads that deal with the subject matter of the Supreme Self or Brahman. They teach us how to unfold the divinity within us and reach the Supreme Self. The Upanishads are fairly complex and deal with a very subtle subject. In the Bhagavad Geeta, Lord Krishna has simplified these subtle concepts and made it easier for us to understand.
In this world, we always face choices to make regarding what is right and what is wrong, pleasant and unpleasant, simple and hard and so on. Our problem is that we suffer throughout our life since we do not make the right choice at the right time.
In the battlefield of our life, we are not fighting against other people but we often have to choose between right and wrong and try and do things that are appropriate to situations. Most problems occur in our life because we do not have a guide, a book or a road map that tells us which way to go. If the Bhagavad Geeta is followed, listened to and understood, it will help us to make the right choice. It is a very clear guide that outlines for us various alternatives and paths that one is faced with. It clearly demarcates the right path that one should choose when faced with a doubtful situation. Shakespeare expressed this very beautifully in one of his famous masterpieces. He said “To be or not to be is the question.” Our situation very often in life is the same, when we do not know how to act, deal with others and face life’s problems. Often we think we know the right path but when it is time to act, we develop doubts. We often have second thoughts and start vacillating. At such occasions the Bhagawat Geeta can be our best guide.
If we have our goal clear and our motives good, then our thoughts and our actions will naturally be good. They will lead us in the right direction. This is the central message of the Bhagavad Geeta.