Scott McKnight puts it like this:
I think the glaring question is this: Is it consistent with the grace of the God of the Bible to think one must hear the gospel in order to respond? Or, is it more consistent to think God’s grace would somehow reach each person? Here’s a big one: How does one’s view here impact one’s understanding both of evangelism and missions? Is there a softening going on among evangelicals or is there a more consistent understanding of God’s redemptive work in the world?
The view questioned above is normally called exclusivism. Although this position has the support of the bulk of the New Testament, it does seem just a tad bit narrow for many Christians. Would God condemn to hell the tribal leader who would have accepted Christ had not the missionary died before reaching him?
Consider accessibilism (apparently coined by William Lane Craig), the belief that God’s redemptive work includes some who do not know and who have not heard about Jesus Christ, but that the religions of the world are not designed by God as “instruments” of redemption. This is apparently the view of Richard Baxter; Gerald McDermott thinks there are inklings of such a position in Jonathan Edwards, John Wesley affirms it, as did Lesslie Newbigin, Norman Anderson, and Alister McGrath.
Blogger Robert E Mason tells the following story:
A Baptist missionary was witnessing to a Buddhist priest about his faith in Christ. The missionary noticed a tear rolling down the priest’s cheek. Sensing that the time was ripe to invite a commitment to Christ, the missionary asked if the priest was ready to ask Jesus to come into his life. The priest responded, "I know this Jesus; he lives in my heart, but until today I did not know his name."
Accessibilists believe in the uniqueness of Jesus as Saviour but they do not believe that God has confined his application of the saving benefits of Christ’s work to those who are members of the covenant community, now the church. In distinction from some Inclusivists, this position does not claim that the work and grace of Jesus is mediated by other religions.
To find out more about a. you can read Who Can be Saved, a book by Terrance L. Tiessen.
You can follow the full discussion on McKnight's blog.