The gospel is simple. It is the “good news” that Jesus died for our sins, was buried, and was raised on the third day so those believing that message could be forgiven of their sins (1 Corinthians 15:1-5; Acts 2:22-36). Obedience to the gospel is also simple. In the likeness of Jesus’ death, burial, and resurrection, believers are to die to their own sins (repent), be buried in the water of baptism, and be raised to the new life (Romans 6:1-11; Acts 2:37-41).
The gospel is also profound. The subject of the gospel, and object of faith, is no less than the Son of God, the Christ, God the Word who came in the flesh (John 1:1-18; 20:26-31). No mere mortal fully grasps how the infinite God of eternity manifested himself as a Jewish carpenter from Nazareth! No one can truly embrace, with mind, heart, and soul, the idea of the suffering servant at Calvary who shouldered every human sin and endured the wrath of God in humanity's place. We may know the words, but not the melody.
Although the gospel is both simple and profound in its pristine state in Scripture, it is believable and able to give eternal life. Trouble is, like everything else in God's creation, the hand of humanity has managed to pollute the gospel, at its simplest and most profound levels. The resurrection never really happened, “Jesus only rises in the heart of the believer.” Baptism is a symbol, nothing more, nothing less. Jesus is just a man, not God, or just “a” god among other gods. Once pristine, now polluted; humanity tampering with the works of God.