If I may put my 2c worth in
The beginning is neither the beginning of God,nor as Mr G suggests when Jesus became the firstborn,obviously
firstborn is in regard of pre eminence,as he is the firstborn in pre eminance because he redeemed mankind and became the "new adam"
1 corinthians 15.22
21For since by a man came death, by a man also came the resurrection of the dead.
22For as in Adam all die, so also in Christ all will be made alive.
23But each in his own order: Christ the first fruits, after that those who are Christ's at His coming
Jesus redeemed man,and as such is the preminant being,the firstborn of the new creation because by his life and death he created a new type of humanity,that until christ had never existed before.As the type of humanity that was passed on from Adam as a result of dissabedience to the law,left a humanity that could never return to the image of God,because it was tainted with sin.God could do nothing with this type of humanity as it was sentenced to death by the law.
The beginning is easily explained by the bible,Genesis 1.1 clearly tells us,In the beginning=John 1.1
Proverbs 8.23 Says
“I was set up from everlasting, from the beginning, or ever the earth was.”
