“For those who are led by the Spirit of God are the children of God.” Romans 8:14
That verse is clear: if the spirit of God isn’t leading you, you are not God’s child, just as you do not belong to God (see 8:9).
The image of “adoption” tells us that no one is born into a true relationship with God. The fact that we receive our adoption status proves that there was a time when we were lost; we were not naturally God’s children. Originally, we were spiritual orphans and slaves.
Second, the image of adoption tells us that our relationship with God is based completely on a legal act by the Father. You don’t “win” or “earn” or negotiate a parent. It is simply received.
This teaching is clear and important because it is common to hear people assert that “All humans are God’s children.” The biblical evidence for this assertion is Acts 17:29 where Paul does call all humans God’s “offspring” (genos=descendant), which is like calling Henry Ford the “father” of the Model T. The Bible reserves all the richness of the term “children of God” only for those who have received Christ as Savior and Lord.
“Yet to all who did receive him, to those who believed in his name, he gave the right to become children of God.” John 1:12
The status of God’s child is given to those who receive Him. No one has it naturally except Jesus Christ.