When Colossians (a book devoted to the preeminence of Christ) chapter and verse 1:15 speaks of Jesus as the "firstborn over all creation," or "the firstborn of every creature, it doesn't mean having a baby or God giving birth. The terminology of "firstborn" in the Bible is a title of preeminence or supremacy of position, such as Israel being God's firstborn and also David being God's firstborn--it has nothing to do with being born or created when used figuratively. It simply means priority over. The wonderful news is that this represents Christ's position and also that we are "in Christ."
Everything in time and space had a beginning; how do we know this? Simply because time had a beginning both according to the Bible (cf. Titus 1:2; 2 Tim. 1:9) and modern physicists such as Stephen Hawking, who in his book The Brief History of Time, admitted this. We are all captive and slaves to the element and dimension of time. But God is eternal, meaning He is beyond time and the Bible says He created it because it's only a corollary of space and matter, which came into being at the creation (cf. Gen. 1:1), which scientists refer to as the Big Bang. You could counter: So what if there was a beginning or a Big Bang. But the consequences of a beginning is that you must conclude a Beginner! Who set the Big Bang off in scientific terminology (being programmed with some fifty universal constants), because there can be no effects without antecedent causes, something or someone must have caused this phenomenon.
All of us had a beginning because we are in this dimension--the time-space continuum. God is not because He existed before His own creation: "Before Abraham was, I AM," was Jesus' declaration to the Pharisees of His eternal deity. This all adds up to Jesus as the unique preexistent one, contrary to what the sects of Mormonism and Jehovah's Witnesses teach (that Christ was created, evolved, or born). What do the LDS people believe? They adhere to the fact that the Book of Mormon supersedes the Bible and their credo is "As man is, God once was; as God is, man may become." All of creation was a work of the eternal triune God working in tandem: from the Father, through the Son, by the Holy Spirit. But Scripture (cf. Isaiah 43:10-11) says that before God ("Me") no God was formed.
What then is the significance of Jesus' eternity? He alone is self-existent and self-sufficient, needing no one or nothing! He never had a beginning and will have no end which means He is able to save us to the uttermost and can give us eternal life; Christ is always relevant and never obsolete because He always was and will be; Christ's love is eternal and we can count on Him as Mr. Dependable in all our afflictions; Christ never saw us as an afterthought and He never had to change His plans because of Adam's fall--there never has been a Plan B, but God's perfect plan of redemption has always been His will; Christ knows the end, not because of some time machine or telescope into the future but because He decreed it so, and knows how it will all end up with His glory in control and us sharing in it; because He created all things, He reigns over them and is not subject to their authority as we are; and finally, Christ had to preexist in order to be the creator (it's impossible for anything to create itself).
In sum, our faith cannot rest on a more Solid Rock than Christ, the eternal one, who alone is without beginning or end, the Alpha and the Omega of Scripture. Soli Deo Gloria!