It is certainly true that Jesus is the firstborn of all creation:
Ro 8:29
For those whom He foreknew, He also predestined to become conformed to the image of His Son, so that He would be the firstborn among many brethren.
Col 1:15
He is the image of the invisible God, the firstborn of all creation.
Col 1:18
He is also head of the body, the church; and He is the beginning, the firstborn from the dead, so that He Himself will come to have first place in everything.
Rev 1:5
and from Jesus Christ, the faithful witness, the firstborn of the dead, and the ruler of the kings of the earth. To Him who loves us and released us from our sins by His blood--
As is clearly shown in these verses, firstborn refers not to the birth of Jesus, but to His resurrection from the dead.
This is also clearly shown in Acts 13:32-33,
"And we preach to you the good news of the promise made to the fathers, that God has fulfilled this promise to our children in that He raised up Jesus, as it is also written in the second Psalm, `YOU ARE MY SON; TODAY I HAVE BEGOTTEN YOU.'
I'm very sorry some cannot accept the truth of the deity of Jesus as is declared in John 10,
27 "My sheep hear My voice, and I know them, and they follow Me;
28 and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand.
29 "My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father's hand.
30 "I and the Father are one."
The gift of eternal life can only be given by Someone who is God. When Jesus declares "My Father ..... is greater than all," Jesus is talking about position in the Godhead, not that He is not God.
The Jews of Jesus' day certainly knew what Jesus had just said.
31 The Jews picked up stones again to stone Him.
32 Jesus answered them, "I showed you many good works from the Father; for which of them are you stoning Me?"
33 The Jews answered Him, "For a good work we do not stone You, but for blasphemy; and because You, being a man, make Yourself out to be God."
It is the eternal Redeemer, the Lord Jesus Christ, who writes one's name in the Lamb's book of life (Rev. 21:27). If the Jesus one believes in is not this eternal Jesus, then I have serious doubts whether the Jesus they believe in has given them the gift of eternal life according to John 10:27-28.