This is a presuppositional statement assuming that everyone born of man is God's Child. This IS NOT what God says! John 1:12 "But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name," verses the rest of mankind, Ephesians 2:3 "Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest."
First of all, that men are all children of God is in fact what the Bible says—but it is not the only thing the Bible says on the subject. There is a difference between an estranged son and one who remains on good terms with his father. The former is not in line for the inheritance of the father's estate (and, in that sense alone, is not a "son"). The story of the prodigal seems to imply that the estranged son was still loved by his father, but had cut himself off from every benefit of that sonship by rebellion. When he repented, the father did not say, "Here comes my enemy's son, defecting to my camp." He said "
My son was lost, but is now found!" While he was lost (according to Jesus) he was nonetheless his father's son.
We must remember how many ways the father/son language is used in scripture. Jubal was "the father of" all who play stringed instruments. In
that sense (though in no other!), I am one of his "sons." Some are said to be "children of the devil" in contrast to "children of God." This, however, speaks of moral affinity, not, necessarily, family lineage (since the devil has no offspring among humans). Even the expression "children of wrath" (like the similar, "son of perdition") is a Hebraism—not intended to identify anyone's origin (wrath did not give birth to anyone), but, rather, one's inheritance (that is, one's
destiny).
That all people are truly God's children, by virtue of creation (origin) is declared in scripture:
Have we not one Father?
Has not one God created us?
(Mal.2:10)
"As also some of your own poets have said, 'For we are also His offspring.' Therefore, since we are the offspring of God..."
(Acts 17:28-29)
Thomas Allin wrote (quite well, I think),
"We are told God is not the Father of all men; He is only their Creator! What a total misapprehension these words imply. What do we mean by paternity and the obligations it brings? The idea rests essentially on the communication of life to the child by the parent... assuming all the responsibility involved in the very act of creating a reasonable immortal spirit."
Since the language of paternity is used so variously throughout scripture, we must not allow one set of statements cancel out the teaching of others. To say "that the universal fatherhood of God" is "not what God says" is to fail to take all that the Bible says on the subject into consideration and to focus on only one narrow set of statements to the exclusion of others.