BYHISLOVE-
We are saved through our accepting God's mercy rather than his judgement. No one will obtain eternal life through our being good enough, but only through our acepting that God's own work was sufficient to earn for us the salvation which we could never earn for ourselves:
Now we know that whatever the law says, it says to those who are under the law, so that every mouth may be silenced and the whole world held accountable to God. Therefore no one will be declared righteous in his sight by observing the law; rather, through the law we become conscious of sin.
But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify. This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fall short of the glory of God, and are justified freely by his grace through the redemption that came by Christ Jesus. God presented him as a sacrifice of atonement, through faith in his blood. He did this to demonstrate his justice, because in his forbearance he had left the sins committed beforehand unpunished - he did it to demonstrate his justice at the present time, so as to be just and the one who justifies those who have faith in Jesus. (Romans 3:19-26,NIV)
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What then shall we say? That the Gentiles, who did not pursue righteousness, have obtained it, a righteousness that is by faith; but Israel, who pursued a law of righteousness, has not attained it. Why not? Because they pursued it not by faith but as if it were by works. They stumbled over the "stumbling stone." As it is written:
"See, I lay in Zion a stone that causes men to stumble and a rock that makes them fall, and the one who trusts in him will never be put to shame." (Romans 9:30-33,NIV)
Logic would dictate that in order to repay God for Jesus' sacrifice we should obey a set of laws. But if we were capable of obeying any set of laws (other than the ones we ourselves write) Jesus' sacrifice wouldn't have been necessary in the first place. So God's gifts include not only the righteousness necessary for salvation, but also an entirely new nature through which we can lead our lives in accordance with his will:
So I say, live by the Spirit, and you will not gratify the desires of the sinful nature. For the sinful nature desires what is contrary to the Spirit, and the Spirit what is contrary to the sinful nature. They are in conflict with each other, so that you do not do what you want. But if you are led by the Spirit, you are not under law.
The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God.
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control. Against such things there is no law. Those who belong to Christ Jesus have crucified the sinful nature with its passions and desires. Since we live by the Spirit, let us keep in step with the Spirit. Let us not become conceited, provoking and envying each other. (Galatians 5:16-26,NIV)
The motivations listed as 'the acts of the sinful nature' are the root cause of all sinful acts. They are also our original nature, the one we are all born with. Nothing we do which emanates from any of these motivations can be seen as anything other than evil, because the motivations are themselves evil. But we can no more subdue them ourselves than we can change the color of our eyes. We need God's direct intervention in order to accomplish this, and we get that intervention as a result of our accepting his Son's sacrifice of atonement.
As a consequence of our accepting Jesus' sacrifice, God's Spirit comes to dwell within us, and he doesn't come emptyhanded. It is he, rather than we ourselves, who subdues our original, sinful nature, and it is he, rather than we ourselves, who implants within us the new nature that we need in order to successfully live Christian lives. The motivations of this new nature are those listed as 'the fruit of the Spirit', and it is with those motivations as the impetus for our actions, and only then, that the actions have assurance of conforming to what God wants of us. Their importance to everything we do is underscored by the words which immediately follow them: "Against such things there is no law."
So for both our salvation and our proper behavior as Christians our trust needs to rest not in ourselves, but in God. It is God who has accomplished all that is necessary in order for us to obtain eternal life, and it is also God who himself restructures our nature so that we can lead lives worthy of being called 'Christian'. In both instances all is accomplished through his power rather than our own. That is why faith in God, rather than in ourselves, is the foundation of Christianity.
