Great Q. - God proves life eternal through the crucifixion and resurrection. And that word is NOT reincarnation. Two different words completely.
Let me try it this way, not to convert or convince you [that must be of your own choosing], but to be clear for other interested folk who read these answers and Qs long after we have moved onto other things. Also, I was not raised in a Christian environment, but have come to the truth of Christ from knowing God even as a baby in the crib on my belly just beginning to lift my head. I am not a final authority, but speak from the truth I know in my heart.
First, let me define the word 'sin' as found in the Bible
sin = Old Testament - 'misunderstanding' (Hebrew) and also New Testament - 'missing the mark' (a Greek term used in hunting). Think of all the times Jesus said, Go and sin no more...Let he who among you is without sin cast the first stone... God's saying GET IT CLEAR DON'T MISUNDERSTAND THIS ANY MORE, QUIT MISSING THE MARK IN YOUR THINKING.
In the Old Testament God spoke directly to the highest and best of all that God created - man. Adam and Eve had direct communication with God, and still used free-will erroneously. God began to speak directly to less of man as the OT continues, Noah, Moses, etc. By the time of the New Testament, mankind had pretty much been separating mentally and in behavior from God and God's precepts and so, God puts on 'skin' and walks about in what God created, as Jesus - to say something like this,
'Who have you crucified today? Please stop. Love, God.'
In addition to that there is the resurrection point of focus to understand and reemphasize what I just wrote above. God's human creation has been given FREE WILL, so of course humanity is 'allowed' to 'kill' its form. Jesus' demonstration on the cross shows that clearly. And rather than reincarnate (which means to come into a mortal body and die and get reborn into another mortal body) Jesus was RESURRECTED in the same body, complete with the open wounds, they had not 'healed' in the sense of closing up visually. But that did not prevent Jesus, ONLY BEGOTTEN OF GOD, from eating and drinking and walking and talking and teaching after the crucifixion. This is a huge informational lesson that many balk at learning.
Jesus had no sin in him. That too is in the Bible. There could be no sin as God was walking about in a human body temple.
God so loves us that, as a patient parent, we have been given this supreme physical example. Wake up to it has been the request. [reread the above definition of 'sin' and put the 'misunderstanding' definition in place of the word sin, maybe that will help with clarity here]
Spiritual things are spiritually discerned. As long as one looks from the outside at the visual, I can understand how this question arises. But when one looks from the heart and from deep prayerful contemplative meditation, more is revealed beyond words and comprehension and that AH HA moment at last arrives.
People who REALLY believe that Jesus was just a prophet, rarely, if ever, ask this type of a Q. Basically, a seeker is the one who asks this type of a Q.
The fuss comes from people who like to fuss.
From my perspective you are free to believe as you choose.
As for me and my house, we serve the Lord.
And God has three aspects that help us out:
FATHER: Absolute Source, All That IS, The Great IAM, All-knowing (Omniscient), Everywherepresent (Omnipresent), and All Powerful (Omnipotent), Creator, Eternal ONE, Total Love
[Omnipresent part explains it as well].
HOLY SPIRIT: also known as The Comforter. The activity of God.
SON: The Compassionate One, GOD IN HUMAN FORM. The connector (no one comes to the Father except through the Son). Jesus of Nazareth, step-son of Joseph from Bethelem, out of Mary the virgin, chosen among many, grandson of Anne, demonstrated this truth.
This may help some people out there have a better grasp.
But like I said before, spiritual things are spiritually discerned.
Someone once said (I don't remember the source, sorry)
To those with faith no explanation is necessary
To those without faith no explanation is enough.
So, knowing that, I lean not on my own understanding, but on every word which proceeds out of the mouth of God.
May the blessing of God rest upon you
May His peace abide in you
May His presence illuminate your heart
Now and forever more.
I personally worship God. I talk to God directly and also in the name, nature and power of Jesus the Christ. And I am moved and guided by the third aspect of God, the Holy Spirit.
And, as Jesus said, "What is that to you? Follow me."
Thanks again for an interesting Q. :)
Peace be with you.