Note that there is only one Gospel (Galatians 1:8-9), which includes multiple aspects. The core of the Gospel is that we can be initially saved from hell by believing that Jesus of Nazareth is the Christ and the human/divine Son of God (John 20:31, John 3:36; 1 John 2:23) and that He suffered and died on the Cross for our sins and rose physically from the dead on the third day (1 Corinthians 15:1-4, Luke 24:39,46-47, Matthew 20:19, Matthew 26:28).
And the Gospel is that we can be ultimately saved from hell if we continue to believe this to the end (Hebrews 3:6,12,14, Colossians 1:23), and continue to perform good works of faith to the end (Romans 2:6-8; 1 Thessalonians 1:3), and repent from every sin that we commit (Hebrews 10:26-29), and get water-immersion (burial) baptized into Jesus Christ (Mark 16:16, Romans 6:3-11), and partake of Jesus' divine flesh and blood in the bread and wine of Communion (John 6:53; 1 Corinthians 11:23-30), and forgive everyone for everything (Matthew 6:14-15), and do all that we can (Romans 12:18) to make reparations to and peace with everyone whom we have ever wronged (Matthew 5:23-26), and help Christians in need (Matthew 25:34-46), and provide for our families (1 Timothy 5:8), and do not blaspheme God's Holy Spirit (Mark 3:29), and do not remove words from the book of Revelation (Revelation 22:19), and do not worship the future Antichrist (the individual-man aspect of Revelation's "beast") or worship his image or willingly receive his mark (Revelation 14:9-12), but continue in God's goodness to the end (Romans 11:22) and overcome to the end (Revelation 3:5, Revelation 2:26).
Before Jesus Christ acknowledged these aspects of the Gospel to His disciples (e.g. in Matthew 16:16-17, Matthew 16:21, Matthew 26:28), the aspect of the Gospel which He preached was the Kingdom of God (e.g. Matthew 4:23, Matthew 6:33, Matthew 12:28).
(See post #64 above)