Serve through Love
Gal 5:13 You, my brothers, were called to be free. But do not use your freedom to indulge the sinful nature; rather, serve one another in love.
Bondage to legalism promotes hatred for one another. Islam is the more extreme example, but even within Christendom those denominations or individuals with legalistic leanings tend to characteristically display illegitimate contempt for fellow Christians. In contrast love can be more freely exercised among those who are free from legalism. We see this principle in Jesus' ministry where he freely ministered to sinners and healed on the Sabbath, while the legalists not only abstained from such things, but criticized him for doing so.
However on the flip side one can go to the opposite extreme in which one views freedom in Christ as a license to sin. Likewise Peter writes, "Live as free men, but do not use your freedom as a cover-up for evil; live as servants of God." 1Peter 2:16 So feel free to serve.