God’s perfection is to exist. This doesn’t sound very impressive until we consider the opposite of existence. Something that exists is more perfect than the mere conceptualization of that thing. Before Leonardo da Vinci painted the Mona Lisa he envisioned it in his mind. What resulted from his creative powers and artistry continues to fascinate, inspiring legions of impersonators, and bring joy to beholders. Had he not painted it his masterpiece would have disappeared along with his imagination. The Mona Lisa hanging in the Louvre is superior in every way to the unrealized concept.
As the perfection of all that is, God the Father’s knowledge of Himself is perfect. The perfect self-knowledge of the Father exists. It is God the Son. Since Jesus is the perfect self-knowledge of the Father, the Person of Christ has always existed. God the Father and God the Son have no beginning and no end, a truth acknowledged in the Nicene Creed:
We believe in one Lord, Jesus Christ,
the only Son of God,
eternally begotten of the Father,
God from God, Light from Light,
true God from true God,
begotten, not made, one in Being with the Father.