Christianity is not to be used as a weapon against other religions. Instead, its adherents are to live our own lives in such a way that others see us as beneficial to all around us, irregardless of their belief system.
And in order to be truly beneficial, our own code of conduct must be such that others can not only trust, but also be drawn to as comforting. There are motivations which some mistakenly accept as signs of righteousness, and even piety, which are actually signs of what we refer to as 'the sinful nature'. And it's our duty to shun those motivations, and instead welcome the motivations which are taught in Scripture as the core of a new, spiritual nature:
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)
Some of the motivations found listed as 'the acts of the sinful nature' are obvious to all as sinful. Others are more subtle, but no less to be shunned by Christians. Even if a person wraps a motivation from this list in the trappings of piety, it is still to be recognized as sinful.
It is only when we Christians have the motivations listed as 'the fruit of the Spirit' as the impetus for our actions that those actions conform to what God wants of us. The reason why St. Paul preached that we were free from the law was not because he believed that we could do whatever we wanted; it was because for us Christians the law was replaced by the motivations which that law is built upon. Just as we identify 'the acts of the sinful nature' as the root cause of all sinful acts, we identify 'the fruit of the Spirit' as the root cause of all righteous acts. Legalism was replaced with motivationalism. That's why the words which immediately follow the listing of the 'fruit' are, "Against such things there is no law."