Albert Barnes Commentary 1 John 2:23

"Whosoever denieth the Son, the same hath not the Father: he that confesseth the Son hath the Father also." — 1 John 2:23 (ASV)

Whosoever denieth the Son, the same hath not the Father. This means that such a person has no proper understanding of the Father and no evidence of His friendship. It is only by the Son of God that the Father is made known to people (Matthew 11:27; Hebrews 1:2–3), and it is only through Him that we can become reconciled to God and obtain evidence of His favor (see the notes on John 5:23).

But he that acknowledges the Son, hath the Father also. This passage, in the common version of the New Testament, is printed in italics, as if it were not in the original but was supplied by the translators. It is true that it is not found in all the manuscripts and versions.

However, it is found in a large number of manuscripts, and in the Vulgate, the Syriac, the Ethiopic, the Coptic, the Armenian, and the Arabic versions, and in the critical editions of Griesbach, Tittman, and Hahn. It is probable, therefore, that it should be regarded as a genuine portion of the sacred text.

It is much in the style of John, and though not necessary to complete the sense, it well suits the connection. Since it was true that if one denied the Son of God he could have no claim to any proper acquaintance with the Father, it seemed to follow that if anyone had proper knowledge of the Son of God, and made a suitable confession of Him, he had evidence that he was acquainted with the Father. Compare John 17:3 and Romans 10:9.

Therefore, although this passage was missing from many of the manuscripts consulted by the translators of the Bible, and though by printing it as they did, they showed the great caution with which they acted in admitting anything doubtful into their translation, the passage should be restored to the text and be regarded as a genuine portion of the word of God.

The great truth can never be too clearly stated or too often emphasized: it is only by a knowledge of the Lord Jesus Christ that we can have any true acquaintance with God, and all who have a proper understanding of the Savior are in fact acquainted with the true God and are heirs of eternal life.