Will people who have never heard Christ's gospel be damned to hell?

Since without the gospel we were all destined for hell, they believe the fact that God saves anyone at all indicates that He is merciful. But would a just God eternally damn souls to hell if they never had an opportunity to hear Christ's gospel? The argument goes:

"They are given the light of creation (Romans 1:20) and the light of their own conscience (Romans 2:15). If that is not enough to bring them in contact with the gospel of Christ, then they must suffer eternal punishment."

But there is always the nagging question that Evangelicals seem to wrestle with: "What does God do with babies who never understood, people with severe mental disabilities who were never able to comprehend, and souls isolated in the most remote places on earth?" Will a God who is just and loving condemn them to an eternity of punishment? The following scriptures offer some insight on this subject:

But he that knew not and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more.
Luke 12:48

Therefore to him that knoweth to do good, and doeth it not, to him it is sin.
James 4:17

... for where no law is, there is no transgression.
Romans 4:15

But sin is not taken into account when there is no law.
Romans 5:13

[Paul] Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief.
I Timothy 1:13

It is true that we have all sinned (Romans 3:23). The idea that God, by His grace, would stoop to save anyone is a merciful act that none of us earns or deserves. However the above passages make it clear that every person must have an opportunity to hear Christ's gospel before they can be condemned to hell.

How then shall they call on him in whom they have not believed? And How shall they believe in him of whom they have not heard? And how shall they hear without a preacher?.... So then faith cometh by hearing, and hearing by the word of God.
Romans 10:14 & 17

Each person is given the light of creation and their own conscience. However there is nothing in scripture that positively states souls will be lost simply because they have never heard the gospel of Christ. A just God would give every person an opportunity to hear the gospel message. The idea that those who have not had that opportunity will be damned to hell for eternity is a theory and presumption that does not reflect the actions of a God who is loving and just.