How do Trinitarians understand the phrase 'image of God' as in Colossians 1:15?

The Son is the image of the invisible God because he reflects the eternal good will and character of God in the flesh. The perfect character and attributes of God are manifested through the person of Jesus Christ through his suffering and death on the cross. God is blameless in all His ways and so was Jesus during his time here on earth. This perfection of character that Jesus exhibited from birth to death is the reflection of the eternal character of God. It is written that no one has ever seen or can see God but the Son, Jesus Christ has made Him known to you.

John 1:18

No one has ever seen God, but the one and only Son, who is himself God and is in closest relationship with the Father, has made him known.

To see the Christ is to see God, that is why Jesus is being referred to as the image of the invisible God.

God not The Father
There are three reasons why God as it is used here should not be understood as The Father.

• God as used in the OT
• God and Father as used in the NT
• God and Father as used in this letter

The Old Testament makes no mention of God the Father in the sense it is used in the New. Therefore, passages drawing upon the Old Testament (see below), should not qualify God using the new expressions. For example, Paul uses three phrases to specifically identify God as Father. Most common is θεοῦ πατρὸς ἡμῶν, God our Father. Less common is θεοῦ πατρὸς, God-Father, and on a few occasions he employs Sharp's Rule saying, ὁ θεὸς καὶ πατὴρ, the God and Father. None of these terms are used in the LXX. They are New Testament terminology employed to make specific reference to the Father. Therefore, having developed new phrases for the sole purpose of making specific reference to the Father, one must conclude the failure to use the new terminology indicates Father is not intended.

The new terminology is used elsewhere in Colossians:

To the saints and faithful brothers in Christ at Colossae; Grace to you and peace from God our Father. (Colossians 1:2 ESV)

And whatever you do, in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through him. (Colossians 3:17)

In addition, the New Testament practice of distinguishing between God and God as Father, or simply Father, is also evident in the passage in question:

⁹ And so, from the day we heard, we have not ceased to pray for you, asking that you may be filled with the knowledge of his will in all spiritual wisdom and understanding, ¹⁰ so as to walk in a manner worthy of the Lord, fully pleasing to him: bearing fruit in every good work and increasing in the knowledge of God; ¹¹ being strengthened with all power, according to his glorious might, for all endurance and patience with joy; ¹² giving thanks to the Father, who has qualified you to share in the inheritance of the saints in light. ¹³ He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, ¹⁴ in whom we have redemption, the forgiveness of sins. ¹⁵ He is the image of the invisible God, the firstborn of all creation. (Colossians 1)

Therefore, a proper exegesis of image of God, ὅς ἐστιν εἰκὼν τοῦ θεοῦ, should recognize Paul's terminology, τοῦ θεοῦ (the God) cannot be understood as a specific identification of the Father.

image of God - εἰκὼν τοῦ θεοῦ
In other letters, Paul compares Jesus to the first man:

Thus it is written, “The first man Adam became a living being”; the last Adam became a life-giving spirit. (1 Corinthians 15:45)

¹² Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned— ¹³ for sin indeed was in the world before the law was given, but sin is not counted where there is no law. ¹⁴ Yet death reigned from Adam to Moses, even over those whose sinning was not like the transgression of Adam, who was a type of the one who was to come. ¹⁵ But the free gift is not like the trespass. For if many died through one man's trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many. ¹⁶ And the free gift is not like the result of that one man's sin. For the judgment following one trespass brought condemnation, but the free gift following many trespasses brought justification. ¹⁷ For if, because of one man's trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ. (Romans 5)

The expression image of God was used to describe the first man:

And God made man, according to the image of God he made him, male and female he made them. (LXX-Genesis 1:27)
καὶ ἐποίησεν ὁ θεὸς τὸν ἄνθρωπον κατ᾽ εἰκόνα θεοῦ ἐποίησεν αὐτόν ἄρσεν καὶ θῆλυ ἐποίησεν αὐτούς

In Colossians, by employing the phrase image of God, Paul has made another Adam/Jesus comparison. The first man was made according to the image of God. But Jesus is the image of God. Furthermore, by using the general expression of God, Paul eliminates understanding image of the Father, which could be seen as contradicting the equality between Jesus and the Father as stated in the Fourth Gospel. That is, image of God is in harmony with equality with the Father, but image of the Father would imply inequality.

As with his other statements equating Jesus and God, Paul does not "fill in the blank." He does not enumerate the qualities. This lack of specificity is no different than the Hebrew term Elohim. No explanation is given to explain why the singular God is most often identified using the plural Elohim. In a sense, it must simply be accepted as stated. Nevertheless, a lack of "full disclosure" is hardly reason to reject the literal meaning of the text. Paul and other New Testament writers all agree on the most significant God-like quality. Jesus was without sin; He is holy.

Finally, in making this comparison to Adam, Paul had the ideal opportunity to make a more precise comparison to Adam by saying Jesus was made. Yet, not only does Paul avoid language which could imply Jesus was a created being, he makes the point Jesus is. Then he immediately follows with a list of actions the Old Testament states are reserved for God.

For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. (Colossians 1:16)

My Trinitarian Conclusion
First, the expression in the context of the letter demonstrates God is no longer an adequate term to describe divine interaction with mankind. Unlike the Old Testament, theos is not self-explanatory. New Testament writers are compelled to distinguish between God, and God the Father. This change in terminology is exactly what I would expect if those educated under the Old Testament understood the more complete revelation of God as found in the New Testament. In other words, from the Old Testament vorlage, God the Father only makes sense from a Trinitarian understanding of God. Otherwise the New Testament burdens the reader with unnecessary terminology.

Second, by stating Jesus is the image of God, Paul distinguishes between the pre-existent uncreated Son and Adam who was created according to the image of God.

Third, by following image of God with a list of divine actions, Paul reinforces the pre-existent uncreated status of the Son. Moreover, he implies the Son was active in making the first man according to the image of God.

Finally, in addition to other New Testament passages which describe Jesus using God-like terms such as glory or radiance, considering image of God in light of equality with the Father, leads me to conclude Colossians could also be understood as He, the Father, is also the image of God.

The Apostle Paul here describes Christ as "the image of the invisible God." The Bible states in several locations that the essence or substance of God is invisible to human beings (Romans 1:20; 1 Timothy 1:17; Hebrews 11:27).

It also states that no man can ever see God, an obvious reference to the Father, but that Christ has made the Father known (John 1:18; John 14:9).

"Image" expresses two crucial points. First, it suggest "representation, likeness." Hebrews 1:3 reflects the same idea through another Greek term that was translated "exact representation" of His nature, (NASB).

Paul also described Christ as "the firstborn of every creature. "Firstborn" (prototokos) does not imply that Jesus is part of creation, but rather indicates His priority and sovereignty over all creation."

Colossians 1:16 backs this up. "For (or because) by or through Him were all things created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities - all things have been created by Him and through Him."

Not only did Jesus always exist (John 1:1; John 8:58), but He holds all creation together. (Colossians 1:17). So, just as Jesus is supreme over the natural creation, He is sovereign over the new creation, the New Testament Church of which He is head.

Verse 18 establishes the ground for Christ's vital headship of the Church. He is the "beginning" (arche) or "source" or "origin." Jesus is not only the "source/origin" of the Church, He is the origin of creation as confirmed by Revelation 3:14. We get our English word "architect" from the Greek word "arche."

Finally, He is the "firstborn" (prototokos), the first to rise from the realm of the dead in a permanent fashion (Revelation 1:5). On the basis of all these achievements, one can see why Jesus Christ is the "Preeminent One."

"The Son is the image of the invisible God."

In English, there is an idiom that uses the words spitting image. If, for example, I say of Eddie, "Boy, Eddie is the spitting image of his dad," or "Wow! Ruth is the spitting image of her mother," I am saying that the similarity between son and father and daughter and mother is uncanny.

Well, Jesus is the spitting image of his Father.

Philip, one of Jesus's disciples, asked the Master, “'Lord, show us the Father and that will be enough for us.' Jesus answered: 'Don’t you know me, Philip, even after I have been among you such a long time? Anyone who has seen me has seen the Father. How can you say, ‘Show us the Father’?" (John 14:8-9 NIV).

Jesus's disciples, both then and now, needed to be reminded that God the Father is invisible. Jesus reinforced that idea in his conversation with the Samaritan woman at Jacob's well:

"Yet a time is coming and has now come when the true worshipers will worship the Father in the Spirit and in truth, for they are the kind of worshipers the Father seeks. God is spirit, and his worshipers must worship in the Spirit and in truth” (John 4:23-24).

Christians are, however, able to see the Father, with eyes of faith, by looking at Jesus. Some of the first-century believers had the privilege of seeing Jesus with their physical eyes. Subsequent generations of believers were/are not afforded that privilege. They can, however, appeal to the Father through the Spirit of Jesus--again, through eyes of faith.

Jesus the Son is not God the Father; otherwise, why would Jesus address God as his Father? Jesus is, however, fully God and fully man. To this day, Jesus retains his humanity as he sits at the right hand of the Father in heaven (Colossians 3:1; Mk 16:19; Lk 22:69; Heb 1:3 and 13; 10:12; and 12:2) . Like the servant of old who loved his master and did not desire to be freed by his master (see Deuteronomy 15:16-17; cf. Psalm 40:6), Jesus had more than his ears pierced with an aul; he sacrificed his very life at the cross, shedding his blood for the remission of sins. In doing so, he pleased his Father, not as a slave would please his master but as an obedient Son would please his Father (John 8:29).

REVISED CONCLUSION

In conclusion, a person who is less than God has neither the right nor the ability to take away the sins of the world (see John 1:29 and 35). As the sinless and spotless Lamb of God, only Jesus in his full divinity and singular sinlessness could make atonement for sin. Jesus' critics were correct in their belief that only God can forgive sins, but Jesus did just that on more than one occasion (see, for example, Luke 5:20-26, which is echoed in Matthew 9 and Mark 2).

To believe otherwise is to be guilty of heresy of the worst kind. The belief that Jesus had a beginning flies in the face of the belief in a God of love (see 1 John 4:16), since the "love affair" between the Son and the Father is and forever shall be eternal. It has no beginning and no end. To believe otherwise is the fall into the trap of Islamic theology that teaches that Allah is one person and one only, with Jesus being relegated to the status of only a teacher and prophet.