Freewill is one of the many reasons of inculcating various ways of thinking in human beings. Various thought created many ideologies among the societies. These contradictory ideologies are proved to be very dangerous for not only to a group of people but also for people of different observation in the same religion.
Men started to force other men to believe in his concept and methodology. And now a day's a group of people or a group of nation decides the ideology, rules & system for other group of people or nation. This type of influencing forces want other people to live theirs ways and not in God's way. Complexity has taken further steps when God is believed to be divided. Encroachment of thoughts has become the prime reason of enmity among men.
In a recent movie PK we see the observation of a man of other planet. He doesn't find the reason of his thrashing. Ultimately he concludes that there are different group of people having different managers. Each manager has implemented different rules and he must understand these rules to deal with various people. Religious diversity is not a problem. The actual problem is that when few group of people use these tools for political or other type of self gain thereby brainwashing the common men. This is one of prime reason of enmity among the men.
Greed of carving future for assuring tomorrow's comfort is always embedded in the children. They only have the sense of competition. This teaching is prevailing in more or less all parts of the world. Humanity, honesty, integrity is only meaningful for near and dears only. These values are not ensured while dealings with the people of other society or community. Men have become brutal in nature. One innocent person is beaten till death in today's time for political reason. Policies and ideologies are overruling humanity. So we can say that man's greatest enemy is man not a lion or not an elephant. First World War caused the war equipment race among the nation. This brought bigger destruction in Second World War. Human is doing research work day and night to develop sophisticated war equipments. These war equipments have shown its dangerous effect in Iraq and Afghanistan war of 21st century. Therefore we can conclude that man's greatest enemy is man. This enmity is killing human beings at very large scale. Pity, kindness, compassion are existing only on paper in the current century.
Let watch another case. School children are being taught to beat other students in the class to remain safe. In this scenario we see that all the children have same lesson of hatred. The children are learning lessons of cleverness up to such a degree that they maintain it also against their parents. That's why in modern time parents are in loneliness. The children are far away from their religious book. Many of them have not even seen the cover of their religious book. This is the prime reason of failure of human values. They are learning the changed and moulded values of their generation. Thus standard values are getting wiped off. General purpose thinking changes its rule for short term gain. Standard religious values are the primary source to correct mistakes but Today's men are trapped in short term selfish philosophy. Therefore goodness is decreasing thereby creating a man as a biggest enemy of a man.
A mother in law is always the foe of her daughter in law generally in South East Asian nation. This is one of the highest fights among the women that are causing many girls' suicide. This ill will is damaging the women's relationship. Therefore we can say that man's greatest enemy is man.