He was raised in the luxury of his family's wealth. As a Sikh, Sundar was taught about Hinduism and came along with his parents to Hindu and Sikh temples. By the age of seven he had already memorized Bhagavadgita, the intricate Hindu dialogue containing spiritual life lessons. At sixteen, not only had he mastered the Vedas, the ancient sacred books of Hinduism, but he had also read Qur'an, the sacred book of Islam. He then got acquainted with some sadhus who taught him Yoga. A sadhu is a Hindu who devotes his entire life to his religion and forsakes all the worldly pleasures. Sundar remained single and jobless. He travelled all over India wearing a yellow robe without any food and without having any permanent residence. He lived only on the charity of others.

The life of Sadhu Sundar Singh was most remarkable in its Christ-likeness. Being born amidst the depths of Indian culture and religion, and into a Sikh family, during the early part of his life Sundar's mother would take him week by week to sit at the feet of a sadhu, an ascetic holy man, who lived some distance away in the rainforest. It was his mother who first encouraged him to become a sadhu. She once told him, "Do not be selfish and materialistic like your brothers, but seek for your peace of mind and hold steadily onto your faith. Be a sadhu." However, he never achieved peacefulness in his meditations. Owing to his mother's connections with some women from a British mission in Rajpur, Sundar was able to enter the school run by the missionaries. It was there that Sundar was first exposed to the Bible. He wasn't interested in the Bible at that time. Instead, he ardently buried himself in Hinduism and yogic practices.

Still, however hard he tried, he couldn't find the peace he had been seeking for in his own religion. He reached a point in his life where committing suicide crossed his mind. Yet before long Sundar was intent on taking his own life. Sundar had arrived at a point of desperation: he had decided to throw himself under the Ludhiana express if God did not reveal to him the true way of peace.
     Three days after he burned the Bible in front of his father, he woke up at three in the morning and went out into the moonlit courtyard for the ceremonial bath observed by devout Hindus and Sikhs before worship. He then returned to his room and knelt down, bowed his head to the ground and pleaded that God would reveal himself. Yet nothing happened. He was thinking of throwing himself in front of the train that would pass at 5 a.m. every morning behind their house, in the hope that he would find peacefulness in his future reincarnation.
     He had not known what to expect: a voice, a vision, a trance? Still nothing happened, and it was fast approaching the time for the Ludhiana express. He repeated his prayer once again. He lifted his head and opened his eyes, and was rather surprised to see a faint cloud of light in the room. It was too early for the dawn. He opened the door and peered out to the courtyard. Darkness. Turning back into the room he saw that the light in the room was getting brighter. At first he feared that the room was on fire. But nothing happened. He then thought that it might be an answer to his prayer. While watching the light, he suddenly saw Jesus' figure in the radiance. To his sheer amazement he saw not the face of any of his traditional gods, but of Jesus the Christ.
     Jesus Christ was there in the room, shining, radiating an inexpressible joy and peace and love, looking at him with compassion and asking, "Why do you persecute me? I died for you ..." [Acts 9:1-5] At that time, Sundar realized that Jesus was not dead but alive. Sundar fell on his knees before Him and experienced an astonishing peacefulness which he had never felt before. The vision disappeared, but peace and joy lingered within him.

Thereafter his life was transformed. He wanted to be baptized. Although his family tried to prevent him from his intention, he was determined. In 1905, on his birthday, he was baptized in an English church in Simla. At that time, he decided to become a sadhu, so that he could dedicate himself to the Lord Jesus. As a sadhu, he wore a yellow robe, lived on the charity of others, abandoned all possession and maintained celibacy. He was convinced that this was the best way to introduce the Gospel to his people since it was the only way which his people were accustomed to. In addition, he also wanted to be free to devote himself to the Lord.

Having become a Christian, he was renounced by his father and ostracized by his family. On October 16 1905, Sundar wearing a yellow robe, barefooted and without provisions, resumed his nomadic life from village to village, but this time he followed in Jesus' footsteps. From here on the life of Sundar Singh became most Christ-like. Being unwilling to denounce his Master in the face of his family's rejection, Sundar took the saffron robes of the sadhu and began a life of spreading the simple message of love and peace and rebirth through Jesus. He carried no money or other possessions, only a New Testament.

"I am not worthy to follow in the steps of my Lord," he said, "but like Him, I want no home, no possessions. Like Him I will belong to the road, sharing the suffering of my people, eating with those who will give me shelter, and telling all people of the love of God."

Following the advice of his friends, Sadhu enrolled himself in St.John School of Theology in Lahore. After studying for two years there, he resumed his travel. An eyewitness reported his experience with Sundar, "I encountered Sundar Singh as he was walking down a mountain trail to proclaim the Gospel to us. He then sat on top of a tree, wiped the sweat off his face and sang a hymn about the love of Jesus to us. The audience was not impressed by the song. One man came forward from the audience, pulled Sundar down from the tree and knocked him to the ground. Silently, Sundar got to his feet and began praying for these hostile people. He then told us about the love of Jesus who had died to redeem all sinners. Because of that I repented and so did the attacker." That was not the only time when Sundar won souls for the Lord by adhering to Jesus' instruction which says, "Do not take revenge on someone who wrongs you. If anyone slaps you on the right cheek, let him slap your left cheek too." (Matthew 5:39).

One day in Nepal, Sundar was ambushed by four robbers in the middle of a jungle. One of them brandished a sword. Meekly, Sundar bowed his head thinking that his life was about to end. This attitude surprised the perpetrators. Since he was penniless, they took his blanket away from him and let him go. But then, one of the robbers called him back and curiously asked his name. Sundar introduced himself, opened his Bible and started telling him the story of the rich man and Lazarus the poor. The robber said that the end of the rich man's life was unpleasant and asked what would happen to himself. Sundar then told him about the Gospel and God's forgiveness. The robber took Sundar home with him and repented.

In 1912 Sundar decided to imitate Jesus' seclusion and fasting for 40 days even though his friends advised him against it. He failed to fast for 40 days because he became weak. However the experience strengthened his spirit. He could thus overcome all doubts, anger and impatience.

In the following years, he was often persecuted but he was also miraculously delivered by the Lord. In 1914, Sundar preached in Nepal, a country with a very strong root of Buddhism. In the town of Rasa, he was sentenced to death by a local Lama on the grounds of spreading a foreign religion. He was thrown into a dry well the top of which was then covered and locked from the outside. He was without food and drink, naked inside the well together with corpses of executed murderers. He stayed in the horrible well for 2 days until a stranger came and helped him out of the well. After relocking the well, the stranger left without saying anything. Not long after that, Sundar was recaptured and taken to the Lama. The Lama was very surprised since he had always kept the only key to the well with him. Realizing that Sundar was under the protection of a very powerful God, they became fearful of him and begged him to leave them.

In 1918, Sundar visited Madras where thousands of people gathered to listen to him preach. There Sundar focussed his preaching on Jesus Christ the redeemer. He testified, "Jesus' presence always brought astonishing peace to me no matter how bad the situations I was in. Whenever I was in a prison, he was always there for me. He transformed the jail into a heaven and the burdens became blessings. There are many Christians who do not feel His glorious presence as something real. Because for them Jesus only occurs in their minds and not in their hearts. Only when someone surrenders his heart to Jesus can he find Him."

Sundar often used parables in his preachings. He once said, "One day after a long journey, I rested in front of a house. Suddenly a sparrow came towards me blown helplessly by a strong wind. From another direction, an eagle dived to catch the panicky sparrow. Threatened from different directions, the sparrow flew into my lap. By choice, it would not normally do that. However, the little bird was seeking for a refuge from a great danger. Likewise, the violent winds of suffering and trouble blow us into the Lord's protective hands."

Sadhu Sundar Singh journeyed much. He travelled all over India and Ceylon. Between 1918-1919, he visited Malaysia, Japan and China. Between 1920-1922 he went to Western Europe, Australia and Israel. He preached in many cities; Jerusalem, Lima, Berlin and Amsterdam among others. Sundar remained modest despite his fame. His attitude made his father repent. Sundar never thought of himself. He only desired to follow Jesus' example: to repay evil with kindness and to win over his enemies by love. This attitude often caused his enemies to feel ashamed of themselves. Once, he was preaching in a public market when a fanatic from a different religion suddenly punched his right cheek. Calmly, Sundar turned his left cheek towards the assailant. The attacker left. But that night Sundar received a message from the attacker asking for forgiveness. On another occasion, Sundar told some harvesters about the parable of the weeds. They became annoyed and cursed him. One of them threw a stone at Sundar's head. At that instant, the stone thrower was struck by such a painful headache that he had to lie down on the ground. Without hesitations, Sundar took over that man's chore and helped them harvest the crops. They soon became friendly to him and invited him home. Their hearts were then open to the Gospel. The next day after Sundar left, they noticed that their harvest became more abundant.

"I am not worthy to follow in the steps of my Lord," he said, "but like Him, I want no home, no possessions. Like Him I will belong to the road, sharing the suffering of my people, eating with those who will give me shelter, and telling all people of the love of God."

He travelled India and Tibet, as well as the rest of the world, with the message that the modern interpretation of Jesus was sadly watered down. Sundar visited Tibet every summer. In 1929, he visited that country again and was never seen since. Sundar manifested into his life the verse written in Mark 8:35 which says, "For whoever wants to save his own life will lose it; but whoever loses his life for Me and for the Gospel will save it."