Believing for the sake of Christ !
Phil 1:29
29 For to you it has been granted on behalf of Christ, not only to believe in Him, but also to suffer for His sake,
All those who shall believe on Christ as a result of Salvation, it is because it has been granted/given to them to do so. The reason why it has been so granted , was because of His Blood Shed for them, and because its being granted to Him, in other words, He prays that for those He died for to be made believers through the Word of His chosen messengers Jn 17:19-20
19 And for their sakes I sanctify Myself, that they also may be sanctified by the truth.
20 “I do not pray for these alone, but also for those who will believe in Me through their word;
All for whom He died and rose again, them He also maketh intercession for in behalf of in heaven Rom 8:33-34
33 Who shall bring a charge against God’s elect? It is God who justifies.
34 Who is he who condemns? It is Christ who died, and furthermore is also risen, who is even at the right hand of God, who also makes intercession for us.
The word intercession is the greek word ἐντυγχάνω
I meet, encounter, hence: (b) I call (upon), make a petition, make suit, supplication.
It means a prayer to God on behalf of another.
Christ by His Presence before God, constantly intercedes on behalf of all for whom He died, He makes Petitions for them.
Believers are the answer to Christ's petition and intercession. Lets look at a Psalm here Ps 2:7-8
“I will declare the decree:
The Lord has said to Me,
‘You are My Son,
Today I have begotten You.
8 Ask of Me, and I will give You
The nations for Your inheritance,
And the ends of the earth for Your possession.
Hence it was these that Christ interceded for in the Nations, and whom Paul understood would be made obedient to the Faith as Christ's possessions Rom 15:18
18 For I will not dare to speak of any of those things which Christ hath not wrought by me, to make the Gentiles obedient, by word and deed,
The ESV :
18 For I will not venture to speak of anything except what Christ has accomplished through me to bring the Gentiles to obedience—by word and deed,
They are made obedient in the day of His Power Ps 110:3, the day of Gospel Power Rom 1:16
16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
The Gospel power here converting them makes manifest that they were part of the possessions, inheritance the Father gives the Son upon His Intercession for them.
Rom 1:5
5 By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:
Rom 16:26
26 But now is made manifest, and by the scriptures of the prophets, aaccording to the commandment of the everlasting God, made known to all nations for the obedience of faith:
Paul here is asserting that in answer to Christ's Intercession to the Father, the messengers are sent out with the Gospel to all nations to bring about their obedience to Christ, or to faith !
All this obedience is in accordance with Christ's Intercession for those He died world wide, and their obedience to the Faith is granted for His Sake or on His Behalf Phil 1:29
29 For unto you it is given in the behalf of Christ, not only to believe on him, but also to suffer for his sake;
In other words, the privilege of trusting in Christ for Salvation was a bestowing upon all for whom He died and makes Intercession for, and their believing is an answer to His petition of interceding, for Believers are but manifestations of the Son's Redeemed Possessions Ps 2:7-8
7 I will declare the decree: the Lord hath said unto me, Thou art my Son; this day have I begotten thee.
8 Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession.