2 Corinthians 6:13-15 (KJV)
13 Now for a recompence in the same, (I speak as unto my children,) be ye also enlarged.
14 Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
15 And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?
Children Of God Through Faith In Christ Jesus
Those who are led by the Spirit of God are adopted in as sons and daughters of God. We are not automatically called His children at birth.