When it comes to salvation: God the Father, God the Son and God the Holy Spirit work together as one.
God the Father plans the salvation or set the standard of salvation
God the Son (Jesus Christ) fulfill the will of God, execute plan of salvation, the only one who met God's standard of salvation
and how the Holy Sprit works...
first let me present few facts/truth according to the Bible
Truth No.1: Human can't understand the Bible unless he/she is a true believer (or son of God). > see Footnote 1
Truth No.2: If unbeliever can't understand the Bible, there is no way he can understand the Gospel. > see Footnote 1
Truth No.3: Without understanding of the Gospel, they will always choose to reject the salvation offered by God. Because they were blinded by the god of this world (the "enemy"). see Footnote 1
Truth No.4: The heart of man is exceedingly wicked that it will always choose to reject God. Still free will exist though man will always choose to reject God because of his heart that is exceedingly wicked. > see Footnote 3
How can they believe if on the first place they cant understand the Bible? How can they believe the Bible if on the first place they will always choose to reject God. Even with the revelation from God's creation they deny the existence of God. Dito na po papasok ang gawa ng God the Holy Spirit.
God the Holy Spirit will give faith and understanding to those who are elect/predestined. > see Footnote 2
The Holy Spirit is the one responsible giving each man's heart understanding of God's salvation.
in summary, God the Father, God the Son and God the Holy Spirit works together to lead elect's soul unto salvation that he will always choose to believe in God.
In this way, knowing that it is all by God's grace and knowing that it is God's who work unto us to obtain salvation, that we can only glorify God to the fullest.
and i can say this with all my heart:
"To God be the glory for all the things He hath done. He showed me that I am a sinner not worthy of His glory. He led me unto repentance. He saved my soul, He let me understand His Words/Bible. He changed my life from being spiritually wicked to being spiritually righteous. He gave me power over my old self. Though I sinned from time to time here on earth while in my physical body or corruptible body - Jesus washed it by His own blood and became my mediator to God the Father, thus God the Father instead of seeing my sins He sees the Blood of Jesus as redemption of my sins."Footnote 1:
That is because the word of God is not intended to be understood by everyone. It is intended to be understood only by those who believe. That is why the bible says the Gospel is veiled to those who refuse to believe:
3 And even if our gospel is veiled, it is veiled to those who are perishing. 4 In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God. (2 Cor. 4:3-4)
I'm sure you have experienced it many times. Evangelize all you want, until you are blue in the face, and they still won't believe. That's why Jesus explained:
31 He said to him, ‘If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.’ (Luke 16:31)
Footnote 2:
8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:9 Not of works, lest any man should boast. Ephesian 2:8-9
Even "faith" is a gift from God.
Footnoe 3:
The heart [is] deceitful above all [things], and desperately wicked: who can know it?Jeremiah 17:9 KJV
10 As it is written, There is none righteous, no, not one:
11 There is none that understandeth, there is none that seeketh after God.
12 They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one.
13 Their throat [is] an open sepulchre; with their tongues they have used deceit; the poison of asps [is] under their lips:
14 Whose mouth [is] full of cursing and bitterness:
15 Their feet [are] swift to shed blood:
16 Destruction and misery [are] in their ways:
17 And the way of peace have they not known:
18 There is no fear of God before their eyes. Romans 3:10-18 KJV
21 Because that, when they knew God, they glorified [him] not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. Romans 1:21 KJV
Note:
a. Unless you realize that you alone can't save your soul from hell you will come unto repentance nor seek Jesus for salvation.
b. If you still believe that by joining a religion, or by reading a Bible, or by doing good works is necessary for obtaining salvation, you will never come unto repentance nor seek Jesus for salvation.