which he promised beforehand through his prophets in the holy Scriptures,Romans 1:2(ESV)
Paul was a willing bond-servant of Jesus Christ, who was called and set apart unto the gospel of God. This gospel was good news for man. It was glad tidings of great joy and it had been promised beforehand by God to mankind.
This gospel for which Paul was set apart were the good tidings which had been foretold through an army of Old Testament prophets - a gospel which uniquely pointed to the Lord Jesus Christ.
This 'gospel' of God was the One toward Whom the writers of the Scriptures were pointing towards. The seed of the woman in Genesis, the lion of the tribe of Judah, the shepherd King of David and the suffering servant of Isaiah.
The gospel of God, which had been proclaimed by so many of God's servants over the centuries was ready to be proclaimed in all its fullness. These good tidings of great joy was the gospel that God promised beforehand through His prophets in the holy scripture and were the gracious thoughts and actions that God had willed towards fallen humanity.
Man had separated himself from God because of sin - but God reached down from the heaven of heavens in loving-kindness and gracious mercy to sinful, fallen man with the good news of Jesus Christ for He is the centre and the circumference of God's good news.
Jesus Christ is the alpha and omega of God's purpose towards His fallen race. Jesus Christ is the gospel of God which He promised beforehand through His holy prophets in the holy Scriptures - and Paul was God's willing bond-slave who was a chosen instrument of God to carry His name before the Gentiles and kings and the children of Israel.
Thank You Father for reaching out to me and to all mankind with your gospel of Jesus Christ, Who died for my sins and rose again the third day to break the power of sin and death in my life - in Whose name I pray, and praise Your holy name, AMEN