There are many people who lived and died before Jesus was born, who will be in heaven. They had a faith in the One who was to come, though they had not yet seen him (or knew his name).
The truth is that many will be in heaven who have not known the name of Jesus.
And it's the truth that it's only through Jesus that we are saved.
Everyone on this thread, though, has heard the name of Jesus, and is without excuse....
In your theory, those who had a sense of God but were pagans, worshipped idols, whatever....all could be saved as long as they had a sense that "god" would send a "redeemer" to give them eternal life.