Second, The Gospel is of Christ
Paul said, "I am not ashamed of the gospel of Christ." Christ and only Christ was sent by God to save sinners. Apostle John testified saying, "... we have seen and testify that the Father has sent the Son as Savior of the world. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God." I John 4:14-15. If the gospel is the power of God to salvation for anyone who believes, such power is wrapped up in Christ and Christ alone. Acts 4:12 says "... there is no other name under heaven given among men by which we must be saved.” but the name of Christ. It is also written, "For there is one God and one Mediator between God and men, the Man Christ Jesus." 1 Timothy 2 says. According to the dictionary, a mediator is a person who attempts to make people involved in a conflict come to an agreement. As stated before, since the fall of Adam and Eve, all fell with them; consequently, all became enemies of God. The bible says, "And they heard the sound of the Lord God walking in the garden in the cool of the day, and Adam and his wife hid themselves from the presence of the Lord God among the trees of the garden." Genesis 3:8.
Adam and Eve changed from friends to enemies, from seekers of God to hiders, from trusting God to being afraid of Him, all because of their sins. Likewise, all their descendants went their own way. Romans 5:12 says, "Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned— ". Every descendent of Adam became automatically an enemy of God. But God who is rich in mercy sent Jesus Christ as a mediator to reconcile us with Him; therefore, the gospel if of Christ. The bible says "Now all things are of God, who has reconciled us to Himself through Jesus Christ, and has given us the ministry of reconciliation, that is, that God was in Christ reconciling the world to Himself, not imputing their trespasses to them, and has committed to us the word of reconciliation." II Corinthians 5:18-19. Reconciliation was made possible only because of the substitutionary sacrifice of Jesus Christ. If anyone does not have the Son, He cannot have the Father. In fact, Eternal life is not only believing in God but also in Jesus Christ whom He has sent. John 17, 3 says "And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent."
Not all roads lead to salvation or to The Father, the way matters: Jesus is The way, not one of the ways. Jesus Himself emphatically declared, “I am the way, the truth, and the life. No one comes to the Father except through Me." John 14:6. The preceding words came about in an occasion when Jesus was responding Thomas, a disciple of His, a Jewish man who was taught the ways of God since his youth, and worshipped the true God, yet he had to believe that Jesus was the savior that God promised to send in Isaiah 53; otherwise, he would not be saved because, again, eternal life is not only believing God but also in Jesus whom He sent. The conclusion then is simple and clear, "... God has given us eternal life, and this life is in His Son. He who has the Son has life; he who does not have the Son of God does not have life." I John 5:11-12. Moreover, it is written, "He who comes from above is above all; he who is of the earth is earthly and speaks of the earth. He who comes from heaven is above all. And what He has seen and heard, that He testifies; and no one receives His testimony. He who has received His testimony has certified that God is true. For He whom God has sent speaks the words of God, for God does not give the Spirit by measure. The Father loves the Son, and has given all things into His hand. He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him.” John 3:31-36. So, the gospel is the gospel of Christ and not one else. Jesus and Him alone satisfied all the legal demands for our justification.
Romans 6:23 says "the wages [salary] of sin is death..." As it is naturally known, anyone that works deserve a wage, it is not a gift but a right. Romans 4:4 says "... to him who works, the wages are not counted as grace but as debt." It is a rightful wage, and God will owe no man but will instead give to each according to their own works. Therefore, every person that sins deserves their rightful wage: death (Ezekiel 18, 20); However, " … God, who is rich in mercy, because of His great love with which He loved us," (Ephesians 2:4), decided to show mercy to humans and forgive their sins. However, for mercy to be extended, the legal demands had to be satisfied. Christ died in our place to satisfy the death penalty imposed by sin so we could be justified - considered no guilty by God. Thus, those who believe in Him can have eternal life instead of death. While the wage of sin is death, the free gift of God is eternal life in Christ Jesus (Romans 6, 23). Another demand of justification is shedding of blood for cleansing and forgiveness of the sins of the offenders. The bible says, "In fact, according to the law of Moses, nearly everything was purified with blood. For without the shedding of blood, there is no forgiveness." Hebrews 9:22.
Based on this requirement of the law, the old testament priest would sacrifice animals on the altar and take their bloods to the holy of holies to make atonement for the sins of the people and his own sins. Leviticus 17, 11 says "For the life of the flesh is in the blood, and I have given it to you upon the altar to make atonement for your souls; for it is the blood that makes atonement for the soul." The word translated atonement is the Hebrew word, kaphar, it means appease, to cover over, pacify, make propitiation. The blood of animals were enough to appease God temporarily only not permanently in regard of forgiveness of sin; hence, the bible says, "The old system under the law of Moses was only a shadow, a dim preview of the good things to come, not the good things themselves. The sacrifices under that system were repeated again and again, year after year, but they were never able to provide perfect cleansing for those who came to worship. If they could have provided perfect cleansing, the sacrifices would have stopped, for the worshipers would have been purified once for all time, and their feelings of guilt would have disappeared. But instead, those sacrifices actually reminded them of their sins year after year." Hebrews 10:1-3. But Christ offered a more excellent sacrifice.
The bible says "But Christ came as High Priest of the good things to come, with the greater and more perfect tabernacle not made with hands, that is, not of this creation. Not with the blood of goats and calves, but with His own blood He entered the Most Holy Place once for all, having obtained eternal redemption. For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean, sanctifies for the purifying of the flesh, how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?" Hebrews 9:11-14. The redemption of souls is expensive (Psalm 49, 8), but Jesus paid it all through His death and the shedding of His blood. Glories to God! It's written, "For by one offering He [Jesus] has perfected forever those who are being sanctified. […] Now where there is remission of these, there is no longer an offering for sin." Hebrews 10:14,18. This perfect sacrifice can be effective in your life, if you repent of your sins and believe Jesus (Acts 16, 29-31) because Jesus and Jesus alone paid for your justification, therefore no one can be saved by any other mean but through the gospel of Christ.