1 Peter 2.24: 24 He Himself bore our sins in His body on the tree [ξύλον], that we might die to sin and live to righteousness; for by His wounds you were healed.
Acts 5.30: 30 The God of our fathers raised up Jesus, whom you had put to death by hanging Him on a tree [ξύλου].
Acts 10.39: 39 And we are witnesses of all the things He did both in the land of the Jews and in Jerusalem. And they also put Him to death by hanging Him on a tree [ξύλου].
Acts 13.29: 29 And when they had carried out all that was written concerning Him, they took Him down from the tree [ξύλου] and laid Him in a tomb.
Barnabas 8.5: 5 Then there is the placing the wool on the tree [ξύλον]. This means that the kingdom of Jesus is on the tree [ξύλου], and that they who set their hope on Him shall live for ever.
We also know that the shape of the cross is thought to be something like a tau:
This shape lends itself to the image of outstretched arms or hands:
There are passages which specifically align the image of a tree with outstretched arms:
So let us imagine for a moment that the following poems are actual songs to be sung in worship:
Odes of Solomon 42.1-6: 1 I stretched out my hands and approached my Lord, 2 for the stretching of my hands is His sign. 2 My expansion is the outspread tree which was set up on the way of the Righteous One. 4 And I became of no account to those who did not take hold of me and I shall be with those who love me. 5 All my persecutors are dead; and they sought after me who hoped in me, because I was alive. 6 And I rose up and am with them; and I will speak by their mouths.
Could Odes such as these be what lies behind this verse in Galatians?
Could it be that this "public portrayal" of Jesus Christ as crucified is actually a posture adopted during worship meetings? (Modern charismatic or Pentecostal Christians adopt all sorts of symbolic postures during their worship, and I have seen my fair share of outstretched hands during such meetings.) Could it be that Paul taught them songs and worship postures, which were the public display he refers to here?
Ben.
ETA:
Tertullian, On Prayer 14: 14 Though Israel wash every day, in all his members, yet is he never clean. His hands at all events are always unclean, crusted over for ever with the blood of the prophets and of the Lord himself: and therefore being, through consciousness of their fathers' guilt, criminals by inheritance, they dare not lift them up to the Lord, lest some Isaiah cry out, lest Christ be horrified. We however not only lift them up, but also spread them out, and, modulating them by the Lord's passion, in our prayers also express our faith in Christ.
Minucius Felix, Octavius 29: Crosses, moreover, we neither worship nor wish for. You, indeed, who consecrate gods of wood, adore wooden crosses perhaps as parts of your gods. For your very standards, as well as your banners; and flags of your camp, what else are they but crosses glided and adorned? Your victorious trophies not only imitate the appearance of a simple cross, but also that of a man affixed to it. We assuredly see the sign of a cross, naturally, in the ship when it is carried along with swelling sails, when it glides forward with expanded oars; and when the military yoke is lifted up, it is the sign of a cross; and when a man adores God with a pure mind, with hands outstretched. Thus the sign of the cross either is sustained by a natural reason, or your own religion is formed with respect to it.