You treat "eternal life" as if it were something which people take ownership of and permanently possess as one might possess a commodity...but this is not what scripture says. Until the last judgement we possess His life provisionally not permanently. Aside from this, we cannot have life at all apart from Him. Jesus Christ Himself IS the life and our hope of glory. We "have" life derivatively as we continue to live in Him.
When Jesus spoke on this subject He told His disciples,
4 Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. 5I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing (John 15:4-5)
The branches are dependent on the vine and receive the life-giving sap on an ongoing basis. As they continue to remain in the Vine they continue to experience God's life, which is eternal life. The very fact that "abide" is a present tense verb in the imperative mood indicates that (1) we have a part in "remaining and "continuing" in Christ and (2) we could refuse to abide if we so chose. This is evident in verse 6:
6 If anyone does not abide in me he is thrown away like a branch and withers; and the branches are gathered, thrown into the fire, and burned (John 15:6).
This same metaphor which shows eternal life as something living and ongoing (rather than a static legal state) can be found in the preceding chapter:
14 But whoever drinks the water I give him will never thirst. Indeed, the water I give him will become in him a fount of water springing up to eternal life.” (John 14:14)
Had this scripture gone no further than the underlined sentence your idea, that eternal life is a one time permanent deposit would be supported. The rest of the verse presents the life of God as an ongoing process in us.
I know your camp tends to slice and dice the scriptures and to remove those parts that are inconsistent with your theology. I have always had more respect for your handling of scriptures than I have for most others in your camp. Still, I feel compelled to put something down from the Apostle Paul on this subject:
20 ...Because of unbelief they were broken off, and you stand by faith. Do not be haughty, but fear. 21 For if God did not spare the natural branches, He may not spare you either. 22 Therefore consider the goodness and severity of God: on those who fell, severity; but toward you, goodness, if you continue in His goodness. Otherwise you also will be cut off. 23 And they also, if they do not continue in unbelief, will be grafted in, for God is able to graft them in again (Rom. 11:20-23).
The word "continue" (epimeno) is a derivative of the same word "abide" that was used in John's gospel. The epi (on) has the effect of intensifying the word so that it emphasizes continuing on with persistence. The language of cutting off also parallels Jesus' remarks. The Roman believers are being told that they would see the "goodness" of the fulfilled promise only IF they continued in the word that had saved them. In context it means not turning from the faith and falling into unbelief. The fact that they needed to be warned shows that apostasy was just as possible for believers as it had been for the Jews who rejected Jesus.