What happens to people who have never heard about Jesus?
In John 14:6 Jesus says "I am the Way the Truth and the Life: no man cometh unto the Father but by Me."
What are the implications of this statement with regards to those that have never heard of Christ? I'm thinking specifically of those who lived before he was born, and those who, even after his birth, never hear anything about him (for example people who live in tribes in the Amazon). Are these souls doomed to suffer in hell for eternity, and if so how is that just?
Also, how does the fate of these lost souls affect my fate as a Christian, given that Christ commanded us to spread the Gospel?