Here is a good example in the Bible of how:
1. Believing in Jesus is the only way to heaven. Just believing in GOD and being good is not enough.
2. A truly good person, like the Dalai Lama, who has never heard of Jesus will hear of Jesus one way or another. God will provide some way for that person to hear the good news about Jesus before that person dies.
Acts 10:1-6
At Caesarea there was a man named Cornelius, a centurion in what was known as the Italian Regiment. He and all his family were devout and God-fearing; he gave generously to those in need and prayed to God regularly. One day at about three in the afternoon he had a vision. He distinctly saw an angel of God, who came to him and said, "Cornelius!"
Cornelius stared at him in fear. "What is it, Lord?" he asked.
The angel answered, "Your prayers and gifts to the poor have come up as a memorial offering before God. Now send men to Joppa to bring back a man named Simon who is called Peter. He is staying with Simon the tanner, whose house is by the sea."
Acts 10:34-43
Then Peter began to speak: "I now realize how true it is that God does not show favoritism but accepts men from every nation who fear him and do what is right. You know the message God sent to the people of Israel, telling the good news of peace through Jesus Christ, who is Lord of all. You know what has happened throughout Judea, beginning in Galilee after the baptism that John preached— how God anointed Jesus of Nazareth with the Holy Spirit and power, and how he went around doing good and healing all who were under the power of the devil, because God was with him.
"We are witnesses of everything he did in the country of the Jews and in Jerusalem. They killed him by hanging him on a tree, but God raised him from the dead on the third day and caused him to be seen. He was not seen by all the people, but by witnesses whom God had already chosen—by us who ate and drank with him after he rose from the dead. He commanded us to preach to the people and to testify that he is the one whom God appointed as judge of the living and the dead. All the prophets testify about him that everyone who believes in him receives forgiveness of sins through his name."