When we think of false gospels, a couple of common ones that raise to the top are the false gospel of works based acceptance and the prosperity gospel. In both cases, the gospel is false because our hope and trust is anchored in something other than the completed work of Christ. And let’s be clear, this doesn’t mean that perpetrators of false gospels don’t acknowledge Jesus and his sacrificial work on our behalf. In fact, you’ll find they most likely do. For the most part, they will acknowledge that Jesus is the Son of God who came in the flesh and atoned for our sins without which there is no reconciliation to the Father. They will even talk about grace and forgiveness.
However, what makes the gospel false is when acceptance and approval by God is placed in something other than Christ. This is crucial because Christianity is Christianity because of what God has done through his Son, because of God’s singular plan for redemption based on his promises and work. That God made all creation good but it plunged headlong into sin due to the first man and woman’s disobedience, he began a work starting with Genesis 3:15 to rescue lost humanity from its disconnected and downcast position. When Jesus, quoting the prophet Isaiah, said, “He has sent me to proclaim liberty to the captives and recovering of sight to the blind” he means HE is the only one through whom lost humanity can have redemption. The whole Old Testament pointed to his ultimate victory over sin and death, requiring that belief rest in him as the fulfiller of all promises (2 Cor. 1:20).
But as it is, Christ has obtained a ministry that is as much more excellent than the old as the covenant he mediates is better, since it is enacted on better promises. (Heb. 9:6)
Thus it was necessary for the copies of the heavenly things to be purified with these rites, but the heavenly things themselves with better sacrifices than these. For Christ has entered, not into the holy places made with hands, which are copies of the true things, but into heaven itself, now to appear in the presence of God on our behalf. (Heb. 9:23-24)