“The sacrifice of Christ as an atonement for sin is the great truth around which all other truths cluster. In order to be rightly understood and appreciated, every truth in the Word of God, from Genesis to Revelation, must be studied in the light that streams from the cross of Calvary. I present before you the great, grand monument of mercy and regeneration, salvation and redemption—the Son of God uplifted on the cross
There are probably plenty of reasons why God waited till He had created everything else, before He created man. Obviously the environment was not inhabitable for mankind earlier, but I would like to suggest another reason. If man had been around while God was creating the earth, he might have come up with the notion that he actually had a part in creation.