Letter opening-Phil. 1:1, 2
Paul's Missionary Report-Phil. 1:12-26 etc.
There is more detail in Silva's commentary on this matter, but this outline might suffice for now. My objective in posting the structure of the first 26 verses of Philippians is to show which unit we should consider when trying to exegete 1:19.
Phil. 1:27 actually belongs to a different textual unit. Now this does not mean that 1:27 has no bearing on 1:19; nevertheless, I think that we should be careful before attempting to interpret 1:19 through the prism of 1:27. The same warning could apply to Phil. 2:1; 3:3, and 4:23.
A number of points in the GNT and Phil. 1:19 make me think that Paul is speaking of the holy spirit when he talks about "the spirit of Jesus Christ."
(1) Paul proclaims that both the prayers of the brothers and sisters as well as
the spirit of Jesus will "result in his deliverance" (Emphatic Diaglott) or
his "salvation" (NWT). Scholars are not certain whether the SWTHRIAN mentioned
refers to eternal salvation, deliverance from prison, or vindication in a
legal sense. But regardless of what "salvation" Paul is talking about, he
most certainly has in mind his eternal destiny as well as a possible release
from prison (this may be an example of deliberate ambiguity). But how would
this "release" come about? Would it happen through the mental disposition of
Christ manifested by Paul or through the holy spirit that God had vouchsafed to
Christ? In answer to this question, notice that Paul associates the spirit of
Jesus with the prayers of the first-century brothers and sisters in Philippi
(Cf. Acts 4:23-31).
But why didn't Paul call the "spirit of Jesus Christ" God's spirit if they
are in fact one and the same? Well, remember when Paul reports that
he entreated the Lord three times, begging God to remove a thorn that
evidently plagued Paul for quite some time (2 Cor. 12:8). What was the result
of Paul's prayer? Jehovah told him that His power was perfected in Paul's
weakness. Consequently, the apostle said that he would boast in his weakness, "so
that the POWER of the Anointed" would "abide upon him" (2 Cor. 12:9 Emphatic Diaglott).
Notice that DUNAMIS is first described as God's power, then it is called "the
POWER of the Anointed" (Christ). But how would Paul be infused with the power
of the Anointed? Acts 1:8; 10:38; Eph. 3:16ff all indicate that the power of
God is communicated via His holy spirit. I therefore conclude that Paul
believed that God and Christ work so closely together when imbuing believers
with the holy spirit--as one WT pointed out--that to desire the spirit of
Jesus Christ is to desire the spirit of God.