Secular view: the universal fatherhood of God and universal brotherhood of man
Scriptural view: God is Father to His people, His children, the elect, not all universally.
The word Adoption implies that we are neither God's children by birth nor by rebirth directly.
Jn. 1:12-13 "But as many as received Him, to them He gave the right to become children of God, to those who believe in His name: who were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God." (NKJV)
John 1:12-13 tells us that the privilege of adoption is realized by those who believe. Thus, it follows faith as does justification. The text also says that those who belief have been,~ were~, born of God - i.e. reborn.