Let no debt remain outstanding, except the continuing debt to love one another, for whoever loves others has fulfilled the law. The commandments, "You shall not commit adultery," "You shall not murder," "You shall not steal," "You shall not covet," and whatever other command there may be, are summed up in this one command: "Love your neighbor as yourself." Love does no harm to a neighbor. Therefore love is the fulfillment of the law (Romans 13.8-10).
For the entire law is fulfilled in keeping this one command: "Love your neighbor as yourself." (Galatians 5.14).Holiness -- moral purity -- is loving others.
To be clear, to handle a quick objection that some progressive Christians want to make of that claim, love is not synonymous with liberal tolerance. Kindness and gentleness, still Fruits of the Spirit, perhaps get closer to what might be described as "tolerance". But love, as the culmination and goal of the virtues, is the cruciform and sacrificial love exhibited by Jesus. Tolerance gets nowhere near the love of servanthood, self-expenditure, and self-donation. Especially when it comes to our enemies. Love is not, no matter what Americans want to think, the same thing as democratic liberalism.
Holiness, then, in coming to love others as Jesus loved others, even your enemies, is the hardest and rarest thing in the moral, social, spiritual and political universe.
But the pursuit of this love is the pursuit of holiness, sanctity, saintliness and purity.
Love does no harm to a neighbor, therefore love is the fulfillment of the law. And that includes the holiness codes of the law.
The entire law -- including the holiness codes that conservatives and fundamentalists love to quote at certain times, when it seems expedient so to do -- is fulfilled in this command: Love God and love your neighbor as you love yourself (Mark 12.30-31, Matthew 22.36-40; Luke 10.26-27).