God set us free from the slave market of sin, delivered us out of the domain of darkness and placed us into the body of Christ, cleaned us up from the inside out (our new nature) we are a new creation with our new home in the heavenlies. He set our feet upon a Rock, indwelling us with His Spirit, being sealed with the Holy Spirit, giving us the ultimate hope.
And we got it all free for nothing because there is nothing we can do to save ourselves. God justified us because we believed by faith alone in the gospel (1 Corinthians 15:1-4) for our salvation.
Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures:
1 Corinthians 15:1-4
It is the power of the ‘gospel’ alone that saves mankind because there is no amount of work a person can do to save them from the penalty of sin. Salvation is by faith alone in the finished work of the cross!
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 the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.
1 Corinthians 1:18