This should be very obvious, but we easily forget it. Even in the verses that most directly uphold the full and complete revelation of the Father in the Son, the differentiation of Father and Son are also prominently in view:
"Anyone who has seen me has seen the Father" (John 14:9)
"The Son is the radiance of God's glory and the exact representation of his being, sustaining all things by his powerful word. After he had provided purification for sins, he sat down at the right hand of the Majesty in heaven." (Heb 1:3)
"He is the image of the invisible God, the firstborn over all creation." (Col 1:15)
"...see the light of the gospel of the glory of Christ, who is the image of God... For God, who said, "Let light shine out of darkness," made his light shine in our hearts to give us the light of the knowledge of the glory of God in the face of Christ." (2 Cor 4:4-6)
The Father is perfectly revealed, not by His Twin, not by a Clone, but by Someone who is His Complement. The Father is revealed in His Son, the Firstborn, His Image, His right-hand Man-Priest. Self-differentiation is at the heart of God's revelation. Jesus is not the same as His Father and yet fully reveals Him. More than this - this difference is of the essence of the divine self-disclosure. Self-differentiation in communion is the being of God - all of this is perfectly revealed in, by and through Jesus of Nazareth.
Now to say that Jesus is other to His Father is not an Arian position. On the contrary this is a determination to see Jesus' revelation as a full disclosure of the life of God. It was Arius who would leave us short of full revelation in Jesus. Here we are embracing the otherness of Father and Son as the very deepest revelation of the divine nature. It is because of His equality with the Father that Christ's otherness must be taken as part and parcel of the divine revelation. Because Jesus fully reveals the divine life by speaking of Another, thus He is not obstructing our view of this Other. Rather the interplay of He and the Other are constitutive of the divine life which He reveals. Arius is refuted at the deepest level, and all by heeding this simple truth: God is not revealed in His Twin but in His Son.
This should be so obvious and plain and yet so many take their opposition of Arius in precisely the opposite direction. Their first and fatal move is to maintain that homo-ousios commits us to three-fold repetition. They assume Father and Son are identical from the outset - all in the name of Nicene orthodoxy (of course ignoring 'God from God...'). Now when they approach the eating, sleeping, dying, rising Jesus they must account for these differences while upholding that the Father and Son possess identical CVs. What to do with the discrepancies? Simple. Ignore the fact that Nicea pronounced the homo-ousios on Jesus of Nazareth and instead attribute all discrepancies to a human nature that is distinct from His divine nature. The cost of such a move? Immediately, the otherness of Jesus is not revelatory of the divine nature, in fact it impedes our view of God. To see Jesus is suddenly not to see divine life, but merely human. We have in fact lost the one Image, Word, Representative and Mediator of God. Jesus of Nazareth has become, to all intents and purposes, homoi-ousios with the Father. Question marks hover over everything we see in Jesus as to whether or not we should attribute this to the divine life. We have returned to Arius's problem via another route - we are left short of full revelation in Jesus.
Now if we took seriously the fact that God is not revealed in His Twin but in His Son we would be saved from all of this. Christ's humanity neither commits us to an eating, sleeping, dying, rising Father, but nor does it distance us from a true revelation of God. Instead Christ's eating reveals a Father who provides in our frailties, His sleeping reveals a Father who protects in our weakness, His death reveals a living, judging Father, His resurrection reveals a justifying, reconciling Father. We see into the very heart-beat of the eternal trinity when we see Jesus of Nazareth in all His glorious humanity.
And all because we have remembered the simple adage: God is not revealed in His Twin, but in His Son!