President Ram Nath Kovind has said that Mahatma Gandhi’s philosophy of truth and non-violence is useful for the whole world. He said Gandhiji’s ideas are still relevant to deal with differences on the basis of religion, race, and language. Kovind was speaking after inaugurating a national seminar on spirituality for human and social development in New Delhi today. Stating that more than 65 per cent the country’s population are youth, the President said there is a need to connect them with the thoughts of Mahatma Gandhi. Expressing concern over climate change, he called it the biggest challenge for humanity.