Ever wondered about people who die and never hear the gospel? What happens to them?
Rom 1:20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:
Rom 1:21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Rom 1:22 Professing themselves to be wise, they became fools,
Rom 1:23 And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.
Rom 1:24 Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves:
Rom 1:25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen.
Notice here that God and his power are CLEARLY SEEN,BEING UNDERSTOOD, by the things that are made (Creation).
So God and his existence are clearly seen by looking at creation, for example the complexity of life, the vastness of the universe, the amazing laws of nature, these all point to an omnipotent God in the same way a 2014 Camaro point to that manufacturer.
This is called General Revelation, and it is the first revelation God gives to a man.
Everyone knows this at some point, the passage say that when they knew God they glorified him not as God, so they rejected God, usually because of the responsibility to him that this would bring, it's easier to deny God than to be responsible to him for out actions, because of this denial they end up in a downward spiral in all sorts of wicked depraved sins, and they usually end up in false religions as well, the passage talks about exchanging the truth of God into a lie, basically people create their own concept of God that does not exist, Pantheism and Polytheism are a good example of this.
Another revelation of God is the conscience:
Rom 2:14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
Rom 2:15 Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another
everyone knows deep down inside that lying, murder, stealing, etc are wrong, and this is written on man's heart in his conscience.
The point i am making is if a person refuses to accept the revelation of Creation, and the Revelation of Conscience, then God is not obligated to give the revelation of Christ, this is completely just and fair.If a person is not willing to learn simply addition and subtraction then it is not unjust for the teacher to be unwilling to teach him calculus.
God sends missionaries when he knows there are people who will be receptive.he is all knowing and knows who will accept his gift of eternal life.
People do not deserve to go to heaven because of sin, it is completely just for God to send anyone to hell,without them ever hearing the gospel, because all have sinned and chosen to do wrong in life. this includes people in foreign lands, When God allows sinners to have a chance to hear the gospel, that is called grace, because they do not deserve the chance, But I do believe that if there is anyone who would be willing to get saved, God will in fact allow them to hear the message somehow, the bible says that God is "not willing that any should perish, but that all should come to repentance.", the bible also says that he wills all men to come the knowledge of the truth and wills all men to be saved. Jesus also said that if he be lifted up (referring to the cross) that he will draw all men to himself; this shows that to some degree, God draws all men to Christ, to the degree that a person is willing to let God draw him, he will draw them.
Consider this passage from the bible:
Act 8:26 And the angel of the Lord spake unto Philip, saying, Arise, and go toward the south unto the way that goeth down from Jerusalem unto Gaza, which is desert.
Act 8:27 And he arose and went: and, behold, a man of Ethiopia, an eunuch of great authority under Candace queen of the Ethiopians, who had the charge of all her treasure, and had come to Jerusalem for to worship,
Act 8:28 Was returning, and sitting in his chariot read Esaias the prophet.
Act 8:29 Then the Spirit said unto Philip, Go near, and join thyself to this chariot.
Act 8:30 And Philip ran thither to him, and heard him read the prophet Esaias, and said, Understandest thou what thou readest?
Act 8:31 And he said, How can I, except some man should guide me? And he desired Philip that he would come up and sit with him.
Act 8:32 The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth:
Act 8:33 In his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth.
Act 8:34 And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man?
Act 8:35 Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.
Act 8:36 And as they went on their way, they came unto a certain water: and the eunuch said, See, here is water; what doth hinder me to be baptized?
Act 8:37 And Philip said, If thou believest with all thine heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God.
Act 8:38 And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him.
Act 8:39 And when they were come up out of the water, the Spirit of the Lord caught away Philip, that the eunuch saw him no more: and he went on his way rejoicing.
Notice here is Eunuch reading the old testament scripture who is clearly searching for the truth, so God sends him somebody to explain to him about Jesus.
Consider another example:
Act 16:9 And a vision appeared to Paul in the night; There stood a man of Macedonia, and prayed him, saying, Come over into Macedonia, and help us.
Act 16:10 And after he had seen the vision, immediately we endeavoured to go into Macedonia, assuredly gathering that the Lord had called us for to preach the gospel unto them.
Hope this helps you to understand.