Romans 1:16 (NKJV)
16 For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek.
“For I am not ashamed of predestination for it is the power of God to salvation.” ‘Predestination’ is in italics to stress the irony of the Covenant and Reformed Theology, which denigrate the gospel. What causes salvation in the Reformed tradition; salvation through faith or predestination? Predestination is the cause of salvation. Charles Hodge a leading Reformed Theologian explains the cause of salvation:
The fact that God has predestinated them to salvation is the reason why they are brought to repentance and a holy life. (Charles Hodge) 
This misconception of predestination is from a misunderstanding of Ephesians 1. It is clear from Ephesians 1:13 that salvation is from belief in the gospel. A person is saved after believing. (13 In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise) God determined this method or salvation from the beginning of the world and in his plan, the saved would become holy and blameless before him in love. (Ephesians 1:4 just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love)
Reformed and Covenant theologians do not believe in the power of the gospel. Their hope is election. The gospel is not the power of God for salvation and belief is not optional, it is predetermined in eternity past. The gospel does not have the power to transform, the real power is in election.
If belief in the gospel is not a real transformation but an outward sign of a predetermined salvation by election, then why pretend that the content of the gospel is meaningful? Indeed content is not meaningful for the Covenant and Reformed Theologians. They do not know what the gospel is.
The Westminster Confessions explains the gospel as “faith in the promised Messiah, by whom they had full remission of sins, and eternal salvation.” The gospel by which man are saved is more than this. The Gospel includes the resurrection of Jesus Christ, the resurrection of the saints and salvation by faith alone.
Paul explains the content of the gospel is important. It is through which we are saved. The content of the gospel is simple and easy to understand. Many children are saved through this gospel who do not have doctorate degrees in Christian universities.
The term “gospel” is used 101 times in the New Testament. 71 times the term is used by Paul and 30 times by others. However the content of the gospel has changed. The gospel Paul preached was the final form of the gospel which now saves us. The Gospel which Paul preached and by which we are saved is the gospel presented in 1 Cor. 15:
15 Moreover, brethren, I declare to you the gospel which I preached to you, which also you received and in which you stand, 2 by which also you are saved, if you hold fast that word which I preached to you—unless you believed in vain.
3 For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures, 4 and that He was buried, and that He rose again the third day according to the Scriptures, 5 and that He was seen by Cephas, then by the twelve.
Paul calls the death, burial, resurrection and the witness of the same by the disciples; the gospel. This is a summary of course, as later in the same chapter, he declares faith as vain or empty to those who believe the resurrection of the saints has already happened. In Galatians he is clear salvation is by faith in this gospel and not by the law.
If the gospel was a watered down version of believe that God will be your God then Paul suffered for nothing.
And I, brethren, if I still preach circumcision, why do I still suffer persecution? Then the offense of the cross has ceased.
Circumcision is a synecdoche for keeping the law as the Covenant theologian would say the “Covenant of Works.” A synecdoche is a figure of speech in which a word referring to a part of something is used for the whole of something i.e. White House.
Paul believed in salvation by faith alone and justification that was not by the works of the law. Paul is being persecuted because he is not preaching justification by the law. Certainly the Jews who persecuted Paul believed the water-downed version; God was their God and their children’s God; the Westminster gospel. This content was not enough to save them under Paul’s gospel. Paul was still imprisoned by such people who he called “estranged from Christ, you who attempt to be justified by law; you have fallen from grace.” (Gal. 5:4)
What does it mean “the works of the law?” or to be “justified by law.” Who commanded Israel to live under the law and follow all things written in the law? It was God who gave the law to Israel and God who expected Israel to observe the law. Moses says cursed is everyone who does not follow the whole law. Paul quoting the same verse in the Torah says cursed is everyone trying to follow the law. These are antithetical statements. Israel is keeping the law to become close to God and the Galatians are running away from the law to become close to God.
‘Cursed is the one who does not confirm all the words of this law by observing them.’ “And all the people shall say, ‘Amen!’
For as many as are of the works of the law are under the curse; for it is written, “Cursed is everyone who does not continue in all things which are written in the book of the law, to do them.”
There has been a tremendous change in the dispensation of God. Paul personalizes this gospel by calling it “my gospel.” This gospel differs from the gospel preached by the apostles in that it includes salvation by faith alone and a refinement of the resurrection as the hope of all Christians. The gospel preached by the apostles and Jesus did not include salvation by faith alone. This is a change in the gospel. If one does not understand this change, he does not understand Paul or the gospel of the mystery given to him.
 Charles Hodge, Systematic Theology , 3 vols. (Grand Rapids: Wm. B. Eerdmans Publishing Company,
 VII.3. Man by his fall having made himself incapable of life by that covenant (the Covenant of Works), the Lord was pleased to make a second, commonly called the covenant of grace: wherein he freely offered unto sinners life and salvation by Jesus Christ, requiring of them faith in him, that they may be saved, and promising to give unto all those that are ordained unto life, his Holy Spirit, to make them willing and able to believe.
VII.4. This covenant of grace is frequently set forth in the Scripture by the name of a testament, in reference to the death of Jesus Christ, the testator, and to the everlasting inheritance, with all things belonging to it, therein bequeathed.
VII.5. This covenant was differently administered in the time of the law, and in the time of the gospel: under the law it was administered by promises, prophecies, sacrifices, circumcision, the paschal lamb, and other types and ordinances delivered to the people of the Jews, all fore-signifying Christ to come, which were for that time sufficient and efficacious, through the operation of the Spirit, to instruct and build up the elect in faith in the promised Messiah, by whom they had full remission of sins, and eternal salvation, and is called the Old Testament.
The Westminster Confession of Faith. 3rd ed. Lawrenceville, GA: Committee for Christian Education and Publications, 1990. WCF 7.5