"Nam Myoho Renge Kyo"
It is believed that Lord Buddha was an incarnation of Lord Vishnu who had attained enlightenment and became a Buddha.
Nam means showing your devotion Myoho is the mystic law. Renge is the Lotus Sutra written by Lord Buddha. Kyo is the manifestation of the mystic law within the lotus sutra in our life.
By chanting this Mantra we can achieve high life condition and eventually Buddhahood. This is so because when people started worshipping Buddha as God he explained that the God is within us. We have to just awaken our potential to achieve enlightenment. He further explained that all the good and the evil is within us. Buddhist believe that human beings go through continuous struggle between good and the evil which are within us. If we create good Karamas(action) we get good results. So we are the creator of the cause and the effect.
While we chant for the happiness of others and spread teachings of Buddha we are creating a lot of good furtunes for ourselves and we are expiating our bad Karamas (actions) which help us to enjoy high life conditions.
By reciting this Mantra our all wishes also get fulfilled and enlightenment is attained. While we are chanting it alleviates our life conditions and we are able to distinguish between good and evil, and we can make out that what is good for us.