Yes that verse does say God will judge justly, but according to whose standard of justice? Romans 1 still very clearly says that God has revealed Himself to mankind in a way that leaves them without excuse, and John 3 still says that without believing in Jesus we are already under condemnation. If we truly believed that those who never heard the Gospel would have that fabled "one last chance" when they stood before God than we need to STOP preaching and teaching because by the very fact of our preaching we are eliminating that "one last chance". What it all comes down to is this. Yes God is a just God but it is His sense of Justice that He holds Himself to not ours, God in His justice has declared the world guilty before Him (Romans 1) and declared what the sentence would be for that guilt (Romans 5). God in His mercy has given a way of escape in the person of Jesus His Son and His atonement for our sins and God has stipulated that this is THE only way to be saved. God has also commanded and commissioned His church to take this message to the whole world and preach the Gospel of salvation and forgiveness in Christ and Christ alone. There is no other way, there is no plan b. None of this is vague or hard to understand. We just don't like what it says.
That, in a nutshell, is the problem. God is speaking, people are just not listening.