Jesus said, "The time is fulfilled and the kingdom of God is at hand, repent and believe in the gospel." (Mark.1.15). I would like to take the time to define and explain to you, those three words; REPENT, BELIEVE, and GOSPEL, because they are clouded with much misunderstanding and misrepresentation by men.
First of all the Bible was not written in the English language. In fact, the English language did not even come into existence as a language until about 1000 years after the Bible was completed. The Old Testament (the first 39 books of the bible) was written primarily in an ancient language called Hebrew and some Aramaic. The New Testament (the last 27 books of the bible) was written in Greek, because Greek was the written language at the time of Jesus and His apostles.
The English word GOSPEL is translated in scripture, into English from the Greek word εὐαγγέλιον (EUAGGELION); which means good news. Now here is a summary of the good news about Jesus that I also received. "For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." (John.3.16). Jesus came in human flesh, and lived a righteous, perfect life; a life that you and I have not lived nor even can, but nonetheless is the life required by God for eternal life with God in His Heaven. Jesus promised eternal life, not to everyone who is perfect, but to everyone who believes in Him. This is good news, because we have all sinned and fallen short of the glory of God, and the punishment for sin is death and hell. Jesus willingly laid down His own life on the cross for His sheep, for our sins against God. He was crucified, nailed to a cross of wood and died. He was buried, then on the third day the very Man who promised eternal life to everyone who believes in Him, walked out of the grave alive. After His resurrection He first appeared to the women, then to two men on the road to Emmaus (a city outside of Jerusalem), then to Peter, then to His other apostles, and then to over five hundred brethren at one time; presenting Himself alive after His suffering, by many convincing proofs, appearing to them over a period of forty days and speaking of the things concerning the Kingdom of God.
The English word BELIEVE is translated in scripture, into English from the Greek word πιστεύω (PISTEUŌ); this type of believing is more than a simple acknowledgement of the truth, it is an implicit trusting, to entrust. Jesus said to Martha, "I am the resurrection and the life; he who believes in Me will live even if he dies, and everyone who lives and believes in Me will never die. Do you believe this?" She *said to Him, "Yes, Lord; I have believed that You are the Christ, the Son of God, even He who comes into the world." (John.11.25,26). She trusted in Him.
The English word REPENT is translated in scripture, into English from the Greek word μετανοέω (METANOEŌ); which means to change one's mind, to think differently. Jesus said to Nicodemus, "Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God." (John.3.3).
Change your mind towards the way that you see God the Father, and Jesus the Christ, His only begotten Son, through Whom and for Whom all things were made; that the world was not made for you, but for Jesus, and you were made to worship Him. Change your mind towards the way that you see your neighbor; that they are either a man or woman created in the image of God and should be loved. Change your mind towards the way that you see yourself; that you are a sinner fallen short of the glory of God, and are deserving of death and hell.
Change your mind from unbelieving to believing, from mistrust to trust, and come follow Jesus! Jesus said; "My sheep hear My voice, and I know them, and they follow Me; and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father's hand. I and the Father are one." (John.10.27-30).
Change your mind and believe that Jesus is the Christ the only begotten Son of God, trusting in His promise of eternal life given to everyone who believes in Him. "The time is fulfilled and the kingdom of God is at hand, repent and believe in the gospel." (Mark.1.15).