Vv 8-9. God saved you by his grace when you believed. And you can’t take credit for this; it is a gift from God. Salvation is not a reward for the good things we have done, so none of us can boast about it.
If salvation depended on doing something of merit, or being from a certain background and culture, not one of us could ever be accepted by God. The fact is that our sin is too deep and our lives too stained to ever merit God’s kindness. If we ever think we can achieve salvation by being just good enough, or marginally better than others around us, then we have missed the point of the Christian message. Salvation from the consequences of sin is a gift from a God of Grace and kindness. And you will never have grounds for boasting about something you might have achieved. Paul could not be clearer; Salvation is not a reward for the good things we have done.
This has long been a British problem. It was a British monk named Pelagius of around 400 AD who taught that Grace was having free will, and the teachings of Jesus, and thus the ability to choose the right way to live and avoid the consequences of sin. In other words, salvation could be gained by knowing what God wanted and then freely choosing the right way to live. This was eventually regarded as heresy. We acknowledge that our human nature is essentially ‘fallen’ or is corrupt, to the point at which perfect obedience to the will of God is impossible.
It is God, in His grace and infinite kindness, who accepts us all on the basis of faith, or total trust, in Jesus. Hence Paul is able to write; God saved you by his grace when you believed. And you can’t take credit for this; it is a gift from God.