God's common grace is to all. For example, common grace gives us rain with fruitful seasons, providing for the natural needs of all mankind. God's goodness to all is common grace. Yet, common grace is not saving grace. God's saving grace is in Christ.
Saving grace is in Christ alone. The only way that we can have a personal relationship with God is through saving grace in Christ. He must reveal himself to us and in us. That has been appropriately called amazing grace. It's not what we do for God. It's what God has done for us in Christ. All that we are or ever hope to be is by the grace of God.
Saving grace is in the gospel of Christ (1 Corinthians 15:1-4). Every believer's testimony echoes the words of the apostle Paul, "But by the grace of God I am what I am, and His grace toward me was not in vain" (First Corinthians 15:10). Grace gives all the glory to God. That's because saving grace is in Christ alone (John 14:6; Acts 4:12).
Saving grace is freely given in Christ. There is no way we can merit nor earn the favor of God. It comes to us only as a gift freely received (Ephesians 2:8-9). Faith in Jesus Christ receives the saving grace of God. Don't fall for the idea that we can somehow be good enough to merit God's favor. Saving grace is not for good people. Saving grace in Christ is offered to sinners, and that includes all of us (Romans 3:23).