1John 1:2 (For the life was manifested, and we have seen it, and bear witness, and show unto you that eternal life, which was with the Father, and was manifested unto us)
These are the facts given by John of eternal life: People can have it by believing on Christ and God (John 3:15-16, 36; 5:24; 6:40, 47). It becomes a well springing up in the soul (John 4:14). People must gather fruit unto life eternal (John 4:36). It comes through searching the Scriptures (John 5:39). People must labour for it (John 6:27). It comes by drinking of (i.e., partaking of) the benefits of the blood of Jesus Christ by faith (John 6:54). Christ has the words of eternal life (John 6:68). Christ gives eternal life to His own who meet the conditions (John 6:27, 10:27-29). God commands people to get it (John 12:50). God sent Jesus to give it to all who come to Him through Christ (John 17:2). To know or to experience God and Christ is eternal life (John 17:2-3). Jesus Christ is that eternal life (1:1-3). This eternal life has actually been seen, heard, and handled (1:1-3). People must not only meet the conditions of eternal life of John 6:27, but they must let (permit) it to remain in them after they get it (2:24). If people do permit (let) it to remain in them, then they will continue in the Son and in the Father (2:24). Eternal life is promised to all (2:25), but it is given only to those who meet the conditions of receiving and keeping it (John 6:27). No one who hates his brother has it (3:15). It comes from God (5:11) and it is only in God’s Son (5:11). All people may know they have it (5:13, 20; John 3:16; 5:24; 17:2-3).
We get eternal life now and keep it forever if we meet the following conditions: Come to Christ (John 6:37, 44, 45, 65); know God and Christ (John 17:2-3); cause no offense (Matt. 18:8-9); forsake all (Matt. 19:27-29; Mark 10:28-30); overcome sin (Rev. 2:7, 11, 17, 26; 3:5, 12, 21); live free from sin (Rom. 5:21; 6:16-23; 8:1-13; Tit. 2:11-14); fight the good fight of faith; lay hold on it (1Tim. 6:12, 19); be sober and hope to the end for it (Tit. 1:2; 3:7; 1Pet. 1:5, 9, 13); endure temptations (Jas. 1:12); love everybody (1Jn. 3:14-15); keep yourself in the love of God, looking for eternal life (Jude 1:20-24); be faithful unto death (Rev. 2:10; Heb. 12:14-15); believe and obey the gospel (John 3:15-19, 36; 4:14; 5:24; 6:40, 47, 54; 2Cor. 5:17; Rom. 1:5); be born again, hear Christ, and follow Him (John 3:1-36; 10:27-29).
BUT eternal life does not become an unforfeitable eternal possession until we enter into it (Matt. 7:13; 18:8-9; 19:17; Rom. 6:22); receive it (Rom. 6:23; Jas. 1:12; 1Pet. 1:13; Rev. 2:10); reap it (Gal. 6:7-8); and inherit it in the world to come (Matt. 19:27-29; Mark 10:28-30; Luke 18:28-30), and at the end of this life (Rom. 6:22).