I often read statements about people who have no knowledge of the Gospel, who have never heard the Gospel, who have never received a Gospel presentation. We say “why should anyone hear the Gospel twice when some have never heard it once?”
But, Biblically speaking, salvation isn’t about knowing the Gospel or even God so much as it is about following and obeying Jesus (James 2:19).
Research indicates people need multiple exposures to the Gospel before they decide to follow.
Further, Rodney Stark’s research on the process of conversion indicates the bigger influence in someone’s decision to follow Christ is relationships with other Christ followers: they do what their friends do (be it church-going or Christ-following) before they ever come to express belief in specific doctrines.
If it is true that obedience precedes belief, and further that relationships modeling what to obey predate obedience, then we should be concerned less with how many times (or lack thereof) a person has heard the Gospel, and more with how many relationships with Christians a person has.
That 86% of Muslims, Hindus and Buddhists do not personally know a Christian is thus a big deal.
Those who have access to the Gospel–those who have heard the Gospel–are mostly people who know Christians (and most of those are due to Christians in their family).
Getting Christians into the daily lives of Muslims, Hindus and Buddhists requires intentional action that is far more challenging than simply purchasing radio broadcast hours, donating to the distribution of Bibles, or leaving tracts in bathrooms.