Irishdub,
Theology will agree with you that the expression "eternal life" speaks of the quality of life, and that it is experienced here and now. In other words, the expression means sharing in the life of the Eternal one. Look particularly at the present tenses in 1 John 5:10-12, and similar.
Let me give you a purely personal unjustifiable hypothesis: "Death created Sin".
By that I mean that some ancient community asked: "Why did the gods not sustain their creation and permit people to die?". They explained something had happened which displeased the gods, and the name they gave to this cause was "sin".
But that does not resolve the problem of why the execution of a Rabbi provides the reversal of death for others. Does the Bible explain, or does it simply assert? Origen's model lasted for 1000 years until Anselm came up with his model.
If God "gave his Son", then Judas, the High Priests, and the Romans were the good people, doing God's work.
Doug