The Gospel, simply put is the story of Jesus. It is Not how we are justified. Justification is the effect of believing in the gospel and isn't something we even need to understand fully for eternal life. So when someone says you must believe we are saved by "faith alone", that is incorrect, and not even taught in the Bible. It is a false premise. We are saved by Grace Alone because it was God's Grace that He provided the free gift of Himself for the whole world, Jesus, to pay the price for sin so that we could be forgiven. So why doesn't everyone have eternal life? The gift was free and for everyone, but in order to receive that Grace we need to cooperate with it through Faith in Jesus. The Gospel is the message that Jesus Christ is the Son of God who came down from heaven, died for our sins and rose on the third day, so that we might attain eternal life and hence be saved. If we believe that and we trust that, then we have faith in Christ, and if we have faith we will follow Christ, and if we follow and believe Christ we will obey his commands and do. However, our faith/trust isn't in what we do, but in Christ. So for that subset of Christians that say good works play absolutely no role whatsoever in salvation, they are incorrect. It is true that "Works of the Law" play no role in our salvation. "Works of the Law" in the New Testament refers to the Old Testament Moasic ceremonial laws. Most Christians I know that claim "Faith Alone" don't actually believe that in practice. When you ask them: "Well is belief necessary, is love necessary, is forgiveness necessary, is repentance necessary ?" they ultimately have to say "yes", because the Bible says they are necessary and those are all things you do.