The Mahatma's Philosophy
Mohandas Karamchand Gandhi became known as "Mahatma" or "Great Soul" because he genuinely tried to live a pure life of: simplicity, nonpossession, celibacy, truth, and nonviolence. These were pillars of Gandhi's own philosophy. He chose to live a life of simplicity because he believed that everything we need is given to us (food, shelter, clothing), all we must do is take only what we need. By doing this, there will be enough food, enough shelter, enough clothing for everyone in the world and therefore by simplistic living, mankind can eradicate poverty. Gandhi also believed in nonpossession: he saw the West as being too materialistic, too industrialized, too selfish. He wanted India (as well as other nations) to be more village-like; helping and depending on others in the community, and sharing when others were in need. Mahatma Gandhi also tried to live a life of celibacy, and was very hard on himself if he failed to do so. His reasoning for this was that a person could not live a spiritual pure life while giving in to the 'lusts of the flesh'. Gandhi was also a staunch advocate for truth. He expressed truth, honesty, and justice in every situation. He even wrote a very truthful (and respectful) letter to Adolf Hitler at the start of WWII. He believed truth prevailed in every situation, and that all mankind should adopt his method of truth. Lastly, Mahatma Gandhi repeatedly expressed his beliefs of non-violence. His belief in non-violence largely stems from his mother, and also from the Jainist community he grew up in. As a result, he could hardly stand the thought of harming any other living being, and therefore he urged India to participate in a non-violent mass movement for independence, and under Gandhi's leadership, India prevailed.
Gandhi was also greatly influenced by the New Testament (particularly the Sermon on the Mount), Muslim doctrine, the Bhavagad Gita, Jainism, Buddhism, and Jainism. He compiled elements of all these religions, and saw value in them all.