We are lucky to have a precious human life, because only this vehicle can take us to enlightenment. There are many religions on the earth, and each has its own way of benefiting beings. The teaching that we are learning now comes from Lord Buddha Shakyamuni. From the Mahayana point of view he is the nirmanakaya form, so his history is basically the same as that of all nirmanakayas: in the beginning practicing bodhichitta, while on the ten perfection path during many lifetimes gathering the two accumulations, becoming a bodhisattva and going to full enlightenment, then turning the wheel of dharma, teaching people.
Lord Buddha was born at the holy place of Lumbini Park. Immediately after his birth, he pointed his finger toward the sky saying his purification and accumulation were complete, that this would be his last birth. Then he took seven steps in the four directions and in each of his steps a lotus sprang up. His nirmanakaya form had to manifest the twelve great deeds, so he studied all the arts, all the various subjects. He took a queen and they had a son, Rahula. Then he left the palace motivated by the tremendous suffering of the local people, particularly the suffering of sickness, old age and death, from which nobody can escape, no matter how much power one has.
After his renunciation he went to practice in solitude. The first two years he ate some rice each day, the second two years just one grain of rice and water and the last two years he lived on oxygen alone; in this way he meditated for six long years. Then he accepted an offering of milk prepared for him from the farmer girl Lekyima, and all 112 nirmanakaya marks appeared on his body. He went to the bodhi tree and made a seat of kusha grass and he sat down with the intention not to rise until full enlightenment. While sitting, he subdued the last of the negative emotional states, the four maras, and then achieved complete enlightenment.
Then he went to Benares, Varanasi Deer Park, and taught the Four Noble Truths. Before him nobody had taught the Four Noble Truths; only Lord Buddha found his answers from his correct meditation. He discovered that sentient beings have tremendous suffering, suffering they cannot escape from, or be protected from. This suffering is created by their own mind because of karma and negative emotions like anger, jealousy, greed, pride and so on. He found that all of this can be purified, that it is not touching the root of the mind. Thus he taught the way to nirvana, the Noble Eightfold Path, and many hundreds of his followers became arhats and enlightened during his lifetime. In his second teaching at Vulture Peak, he taught the Mahayana doctrines to specially qualified people, and to some special people he taught the Vajrayana. Finally, he entered into parinirvana. All his teachings have led numerous sentient beings into enlightenment.
So now, everything we practice comes from Lord Buddha; even when we practice the various deities, these are really the different forms or aspects of Lord Buddha - his wisdom. He has five wisdoms: each wisdom form has a peaceful and a wrathful aspect; so in essence everything is Buddha Shakyamuni Sadhana, or Buddha Yoga. This is for the purpose of leading all sentient beings to full enlightenment, not one left behind. And so, no matter what you learn and practice, especially try to remember Lord Buddha and the great benefit and the great blessing of his nirmanakaya form.
All sentient beings have tathagatagarbha, the true buddha nature or enlightenment, but it is covered by impurities. Buddha nature itself is always pure, like gold; it is the same whether you are a hell being or an enlightened being. Therefore, anyone who remembers buddha nature and Lord Buddha, and then realizes buddha nature by purifying the obscurations that cover it gains enlightenment. So until then, all the time think first: Lord Shakyamuni.
A biography of the Buddha, written by Lama Karma Thinley Rinpoche