One of the most frequently asked questions when I give talks on the history and philosophy of humanism is, "If you don't believe in God and life after death, what's your incentive for leading a moral life?" My answer is, "My respect for others and respect for myself."
One of the basic teachings of humanism is recognizing the dignity of every human being and taking responsibility for how we treat every person we encounter. The daily acts of road rage, the gang shootings, and school yard fights; the political character assassinations, abuse of family members and the brawls in professional sports are not caused by a lack of belief in God, but by a lack of belief in the rights of people.
When people in positions of power and influence demand sexual favors from associates, it's not because they don't believe in a supernatural power, it's because they lack a sense of responsibility that goes with leadership. The ethical teachings of the world's leading religions use the fear of a supernatural power as the enforcer of moral values. Humanism suggests that ethics can and should be based on knowledge and reason, respect for human values that have been outlined by such documents as the Hammurabi Code, the Magna Carta, the U.S. Declaration of Independence, the French Declaration of the Rights of Man, the U.S. Bill of Rights, and numbers six through ten of the Ten Commandments.
Humanists may not believe there is life after death but we do believe in honoring this life. We conclude that the moral problems of this world are not the result of people having lost their religion, but the result of people having lost their humanism.