This is far from the first blog post I have written on this vital topic. While wholly accepting the necessity of Jesus, clearly I find the usual explanations for this necessity, and the usual explanations of just what he did that was necessary, to be unsatisfactory (for one reason or another). This is why I keep trying different ways to explain 'what Jesus did', in the plainest and most comprehensible but (albeit partially) True way that I can. While the reality is what it is, no single explanation works for everyone (for one reason or another) - a new explanation may be the best for some specific person.
1. God is the creator - and God has an eternal body, is separated from that-which-is-created, is localised in space. A body is necessary to be a source of creation.
2. God's aim was that all Men could become divine, live eternally;
dwell-with and participate-with God in the work of on-going creation.
3. Men begin as eternal spirits - but Men cannot become divine unless
each has a body; and for the situation to be permanent, each body must
4. An immortal body cannot be created in one step. This is just a fact, a constraint, of reality. It cannot be known 'why' this constraint exists - but it is the reason that God alone was not sufficient, and that the life and work of Jesus was needed.
5. Jesus was born a mortal Man, and he became fully-divine when baptised by John and the spirit descended and stayed upon him. Jesus was chosen because of his perfect love of God while still a spirit. This meant that Jesus's motivations
were wholly in accord with those of God; such that he could
and would, henceforth, harmoniously participate in creation.
At this point of baptism by John - and because he then became a divine-Man - Jesus made it possible for all other Men to attain life everlasting.
6. At this point (of baptism) Jesus was fully divine and participated in God's creation. Henceforth the work of creation was a 'collaboration' between God and Jesus, with potential for this collaboration to be extended to other Men.
From this point, the miracles of Jesus show harmonious creation in action - including the primary creative act of resurrecting Lazarus, which demonstrated that Jesus really was divine. However, Jesus was still a mortal Man - with a 'temporary' body. To become both divine and eternal, Jesus needed an eternal body.
7. An unique human spirit can only attain to an unique and eternal body via death of the body: biological death must precede the goal of embodied immortality. So, first Jesus's body died, and his eternal spirit remained.
Then, because his (unique) eternal spirit had previously dwelt in a (unique) mortal body, the eternal spirit could 'make' an eternal body specific to that spirit. (Only spirits that have incarnated, may be 'used' to 'make' an eternal, indestructible resurrection-body.)
8. Jesus was therefore the first Man to participate in creation and the second Man to be resurrected. Lazarus was the first Man to be resurrected (by the divine creative act of Jesus); and (although we are not shown this in the Gospels) Lazarus was presumably the second Man to participate in the ongoing work of creation.