the gospel are the actions and words of Jesus Christ as found in Mark, John, Luke and Matthew as is. no need to add anything else Because His words are eternal life. Just listen to Him!
Jesus connected life and salvation directly to His words, not merely to hearing them, but to believing, keeping, and obeying them.
The words that I have spoken unto you are spirit, and are life.
— John 6:63 (ASV)
Verily, verily, I say unto you, He that heareth my word, and believeth him that sent me, hath eternal life, and cometh not into judgment, but hath passed out of death into life.
— John 5:24 (ASV)
Verily, verily, I say unto you, If a man keep my word, he shall never see death.
— John 8:51 (ASV)
If ye abide in my word, then are ye truly my disciples; and ye shall know the truth, and the truth shall make you free.
— John 8:31-32 (ASV)
He that rejecteth me, and receiveth not my sayings, hath one that judgeth him: the word that I spake, the same shall judge him in the last day.
— John 12:48 (ASV)
And I know that his commandment is eternal life: the things therefore which I speak, even as the Father hath said unto me, so I speak.
— John 12:50 (ASV)
Blessed are they that hear the word of God, and keep it.
— Luke 11:28 (ASV)
These verses reveal a consistent teaching from Jesus: His words bring life because they come from the Father. Eternal life is connected with hearing His words, believing them, abiding in them, keeping them, and obeying them. That is why Jesus could say:
The word(s) that I have spoken unto you are spirit, and are life.
John 6:63 (ASV)