Epi with his "inner and outer man"--what about the sarx?
Crucified with Christ - This describes a our spiritual death with Christ some 2000 years ago, a very real supernatural, albeit somewhat "mystical" event that occurred in the past in the eyes of God. The "I" that begins this verse is the old self (= the old man), the evil "I" who was crucified and therefore no longer has a valid claim on our life, for we are no longer in Adam but in Christ. This is now our position before God and it should be reflected in our daily practice.
When we became a believer by grace through faith there was a decisive death to the old (unbelieving, rebellious) self. Now in newness of life we are to work out our salvation (Php 2:12, 13-see notes 2:12; 13) moment by moment by faith in Christ Who loved us and gave Himself for us.
Wil Pounds writes that Galatians 2:20 reads literally "With Christ I have been co-crucified." When I believed on Christ I was so united with Christ, so linked with Him, that I am now so much a part of Him that His crucifixion positionally becomes my crucifixion. A part of me died at the cross. My old carnal nature was slain at the cross. Yet, I don't live in that death. The life I now live, I live in resurrection power. Christ's resurrection has become my resurrection. The life I now live, I live in faith in the Son of God who gave Himself for me.
As alluded to above, the preposition sun (see discussion) speaks of a believer's union or identification with Christ (see "Union With Christ").
The use of the perfect tense is very instructive, signifying that the believer has been crucified with Christ at a specific point in time in the past and that the effects of this this crucifixion persist or continue into the present. Stated another way, the perfect tense speaks of a past completed action having present finished results.
Was not the old nature, corrupt, crucified?
(Romans 6:6) knowing this, that our old self (old man) was crucified with (aorist tense = past completed action) Him, that our body of Sin might be done away with (aorist tense = past completed action), that we should no longer be slaves (present tense = continually) to sin; (see note Romans 6:6)
Comment: Note how God deals with the old self - He does not change it or transform it. What He did was crucify him with Christ. God condemned the old self and poured out His wrath on our Sinless Substitute, Who in turn poured out His blood and gave up His life on our behalf on the Cross. Note the that "was crucified" means "It was done! It was finished!"
We do not need to crucify the old self!
As Dr Walvoord discusses below, crucifixion is not something that we do, but is something that Christ has accomplished for us! "Crucified" is not a command to obey but a fact to be believed! The old self has been decisively dealt with on the Cross! Those who try to conquer the old self in their own strength will only experience futility and will never win the battle! Christ has won the battle for us. Our role now is to yield our will to His Spirit and moment by moment walk out in faith from the victory Christ has already achieved for us at Calvary.
A life filled with resurrection power comes only out of death. In view of the principle that resurrection can only come after death, as believers we must continually reckon ourselves as dead to sin (Ro 6:11-note) with Christ in order to experience His victorious life and His resurrection power, walking by faith and not by sight. Resurrection comes only out of death.)
Come to Me, all who are weary and heavy-laden, and I will give you rest. "Take My yoke upon you, and learn from Me, for I am gentle and humble in heart; and YOU SHALL FIND REST FOR YOUR SOULS. "For My yoke is easy, and My load is light." (Mt 11:28-30)
S Lewis Johnson explains the "I" here writing that "in this case the person in view is the person as dominated by the evil principle of sin, or the flesh -- .
This last sense is the meaning here, in the clause, "and it is no longer I who live." This is the "I" as under the domination of the sin principle. The apostle hastens to add, "but Christ lives in me"… It is in the same person, who formerly was dominated by the sin principle, that Christ lives by the Spirit, but the person has undergone a radical change of direction and domination (cf. 2Cor. 5:17), with new motivation and new desires now implanted by the Spirit through regeneration. The whole tenor of the life has been transformed. The present tense in the verb "lives" stresses that He will never leave us. (Read his full message on Galatians 2:15-21) (Bolding added)
Are you making a distinction, like Epi, re who and what was was co-crucified with Christ?
I'll leave you with this, to use scriptural terminologies--
προφηλώσας αὐτὸ τῷ σταυρῷ). The term "old man" (παλαὶος ἄνθρωπος) occurs also Eph_4:22; Col_3:9. It denotes man’s unregenerate self, when under sin and condemnation; the καινός or νεος ἄνθρωπος being his regenerate self. It is, of course, a different conception from that of ὁ ἐξω and ὁ ἔσωθεν ἄνθωππος of 2Co_4:16. In Ephesians and Colossians the old man is said to be put away, or put off, and the new one put on, as though they were two clothings, or investments, of his personality, determining its character.