When did the world come into being? "In the beginning!" Before the beginning, see Jn 17:5,
Jesus already existed.
TRINITARIANS, two questions...
1) When did the world come into being?
I say about 6,000 years ago.
2) When is “before the world was”?
I say the instant God created the supernatural and spacetime of this universe (right before he created all things within the universe).
John 17:5... And now, O Father, glorify thou me with thine own self with the glory which I had with thee before the world was.
P.S. Here is an overview of what I believe...
(Note: I agree with the view of Melito, Bishop of Sardis around AD 160-180. The following is how I word it.)
For this creation, GOD (the only one who transcends all creations) determined to create a universe with a kingdom of redeemed humans for his glory where he would reign as a human himself. The Scriptures describe how GOD would accomplish his plan. In an instant, eternal GOD (called God the Father) created the supernatural and spacetime of this universe and also became immanent in the universe as spirit (called the Spirit of God) and as a human with a glorious body (called the Son of God). God the Father then created all things within the universe by the power of the Spirit of God commanded by the Son of God (whose name is Jesus). But whereas GOD created a spirit and soul for each of us, GOD himself became the spirit and soul of Jesus. At his conception, Jesus' glorious body was changed to a mortal body to be made like us so he could make reconciliation for our sins. At his resurrection, Jesus' mortal body was changed back to a glorious body and he will also give each of his elect a glorious body when he returns to reign in his kingdom forever.