Jesus eternally existed with the Father. He never had a beginning and he has no end. He is the life made manifest. He created all things, existence was made by him. Death wasn't supposed to be something he was going to have to experience. He was and is immortal. But he chose his death in the flesh. He put on death so that he could raise us all up from our graves to be with him in eternity.
1 John 5:11–12 says
"God gave us eternal life, and this life is in his Son. He who has the Son has life; he who has not the Son of God has not life."
In the same way Jesus chose death, we are given a choice, life or not life.
Most folks who resist faith in the incarnation of Jesus Christ (God manifesting in the flesh), are in part stumbling over the particulars of the spiritual God man becoming a human being in the flesh. But more than that, they stumble over the particulars of an obedient human life of faith in Jesus Christ. They stumble over the particulars that say every single person in the world must obey this one particular person. To accept that particular faith is to give up all control over the particulars of life here on earth. It's too restrictive for them. His particularly perfect example, everything he said and did is law. And his particular life experience in the flesh inspired a written testimony that has universal authority over all particular things. And that particular testimony has formed the foundations of the particular walk of faith in Christ Jesus for millennia. His particular testimony to the truth strips away every pretense. Doing our own particular thing is no longer an option. Jesus' human life, human death, and resurrection from the grave, says to every living person that we are all sin sick and must come to him for healing.
Jesus said, "I am the way the truth and the life."
So it's the particulars of the person Jesus Christ, Son of the living God, that make him both eternal life for some, and a stumbling block for many. Some surrendering their souls to him, and many others resigning themselves to death. For many his particular kingship is authoritarian, he's violating their human selfrighteousness. His life is a law they cannot obey. He's gone particularly too far by commanding them to love God with all their being, and to love one another as He has loved them (especially the loving your enemies part).
I don't know what can be done to remove the stumbling block for many, for some there is no eternal life. All that any of us can do is to continue in the faith, keep doing justice, keep sharing the good news, keep our speech gracious, and seasoned with salt. And keep loving mercy as we walk humbly with God. Keep living that particular born again relationship with Christ Jesus and being a living testimony for his particular truth.