Now this is very telling. Look at all the times the author John mentions eternal life. What is the purpose of the book of John? He tells us at the end of chapter 20: "so that you may have faith that Jesus is the Christ, the Son of God, and so that, having this faith you may have life in his name." He also tells us in the first chapter of 1st John: "We give you word of all we have seen and everything which has come to our ears, so that you may be united with us; and we are united with the Father and with his Son Jesus Christ: 4 And we are writing these things to you so that our joy may be made complete." In contrast the authors of Matthew, Mark, and Luke barely mention eternal life and I can imagine why. Paul's and Peter's letters were at first available to the Gentile churches as well as the Old Testament in Greek. John's gospel was in the hands of the Jews and was not yet available to the Gentiles, and they had a need for a Jesus story. This caused the production of the book of Mark, mostly from hearsay. The Gentile churches had a different purpose for writing a book on the life of Christ: Not to show the reader how to have eternal life, but rather because it is good for business to have the book to read to an audience. Yes, church is a business. It is now, and it was then.
14 As the snake was lifted up by Moses in the waste land, even so it is necessary for the Son of man to be lifted up: 15 So that whoever has faith may have in him eternal life. 16 For God had such love for the world that he gave his only Son, so that whoever has faith in him may not come to destruction but have eternal life.
35 The Father has love for the Son and has put all things into his hands. 36 He who has faith in the Son has eternal life; but he who has not faith in the Son will not see life; God's wrath is resting on him.
13 Jesus said to her, Everyone who takes this water will be in need of it again: 14 But whoever takes the water I give him will never be in need of drink again; for the water I give him will become in him a fountain of eternal life.
36 He who does the cutting now has his reward; he is getting together fruit for eternal life, so that he who did the planting and he who gets in the grain may have joy together. 37 In this the saying is a true one, One does the planting, and another gets in the grain.
24 Truly I say to you, The man whose ears are open to my word and who has faith in him who sent me, has eternal life; he will not be judged, but has come from death into life.
39 You make search in the holy Writings, in the belief that through them you get eternal life; and it is those Writings which give witness about me.
27 Let your work not be for the food which comes to an end, but for the food which goes on for eternal life, which the Son of man will give to you, for on him has God the Father put his mark.
40 This, I say, is my Father's pleasure, that everyone who sees the Son and has faith in him may have eternal life: and I will take him up on the last day.
47 Truly I say to you, He who has faith in me has eternal life. 48 I am the bread of life.
54 He who takes my flesh for food and my blood for drink has eternal life: and I will take him up from the dead at the last day.
68 Then Simon Peter gave this answer: Lord, to whom are we to go? you have the words of eternal life; 69 And we have faith and are certain that you are the Holy One of God.
27 My sheep give ear to my voice, and I have knowledge of them, and they come after me: 28 And I give them eternal life; they will never come to destruction, and no one will ever take them out of my hand.
50 And I have knowledge that his order is eternal life: so that the things which I say, I say them even as the Father says them to me.
2 Even as you gave him authority over all flesh, to give eternal life to all those whom you have given to him. 3 And this is eternal life: to have knowledge of you, the only true God, and of him whom you have sent, even Jesus Christ.
17 And while he was going out into the way, a man came running to him, and went down on his knees, saying, Good Master, what have I to do so that I may have eternal life? 18 And Jesus said to him, Why do you say I am good? no one is good but one, and that is God.
29 Jesus said, Truly I say to you, There is no man who has given up house, or brothers, or sisters, or mother, or father, or children, or land, because of me and the good news, 30 Who will not get a hundred times as much now in this time, houses, and brothers, and sisters, and mothers, and children, and land--though with great troubles; and, in the world to come, eternal life. 31 But a great number who are first will be last: and those who are last will be first.
16 And one came to him and said, Master, what good thing have I to do, so that I may have eternal life? 17 And he said to him, Why are you questioning me about what is good? One there is who is good: but if you have a desire to go into life, keep the rules of the law.
29 And everyone who has given up houses, or brothers, or sisters, or father, or mother, or child, or land, for my name, will be given a hundred times as much, and have eternal life. 30 But a great number who are first will be last, and some who are last will be first.
45 Then will he make answer to them, saying, Truly I say to you, Because you did it not to the least of these, you did it not to me. 46 And these will go away into eternal punishment; but the upright into eternal life.
25 And a certain teacher of the law got up and put him to the test, saying, Master, what have I to do so that I may have eternal life? 26 And he said to him, What does the law say, in your reading of it?
18 And a certain ruler put a question to him, saying, Good Master, what have I to do so that I may have eternal life? 19 And Jesus said to him, Why do you say that I am good? No one is good, but only God.
29 And he said to them, Truly I say to you, There is no man who has given up house or wife or brothers or father or mother or children, because of the kingdom of God, 30 Who will not get much more in this time, and in the world to come, eternal life.