An important controversy in Christianity is the interpretation of whether or not Jesus made exclusive claims where He envisaged no one could come to God except through Him, or whether a biblical theology should allow for the validity of other religions. An important verse used by Christian exclusivists to justify their theology is John 14:6 where Jesus speaks to His Disciples:
Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
What is the best way to understand John 14:6 and why?
It is all about a mathematical model.
With freewill granted to angels, using Law as a measurement tool there will be 2/3 of these angels passing the Final Judgment to enter the final Heaven.
With freewill granted to humans at a much larger degree, using the same set of Law as a measurement tool there will be theoretically less than 1/3 humans passing the Final Judgment to enter the final Heaven.
However with the interaction between humans and angels (angels are present at all establishments from Eden to Earth to the Final Heaven), the 1/3 more capable and more intelligent fallen angels cast bad influence to humans all the times that as an end result no humans are expected to pass the Final Judgment. This is Satan's goal to screw up God's project. Satan directed humans to go the down path. Till Noah it's "proved" under witnesses that humans have no hope to be saved (an alternative expression of passing the Final Judgment). Mankind as a whole shall thus be destroyed by a flood as the purpose of planet earth as field of human soul harvesting is defeated.
With Jesus' self sacrifice at a certain point of history, it makes it possible that humans no longer need to be judged by Law at all. They are instead judged by Jesus/God in terms of a series of covenants. With the judgment of covenants instead of Law, there will be less than 1/3 humans saved through the narrow gate. That's why without Jesus than no humans can be saved as they will all fail the judgment of Law (only the 2/3 angels can pass such a judgment). With Jesus then some are saved through the narrow gate, they are all by means of Jesus' self sacrifice. That's why Jesus remains the only way for any humans to go to the Final Heaven.