From ALL unrighteousness. There is no "forgiving but not forgetting" with God. The world teaches to not forgive, to not trust, to play the victim. Satan wants us bound by the bitterness that breeds from unforgiveness. There are not to be conditions to our forgiveness! We need to forgive as Christ forgave us. That is what the world needs to see from our witness. In a cold and unforgiving world, a Christian who forgives completely. That is how they will know Him. That is how they will see Him!
Lastly, verse 14 binds it all together. It shows us the one virtue that rules them all love. We often think of love in romantic terms but love is so much more than that. God is love. When teaching His disciples about how the world will know believers, Jesus taught:
"A new command I give you: Love one another. As I have loved you, so you must love one another. By this all men will know that you are my disciples, if you love one another." John 13:34-35
And Jesus raised the bar even higher:
"You have heard that it was said, 'Love your neighbor and hate your enemy.' But I tell you: Love your enemies and pray for those who persecute you, - Matthew 5: 43-44
The world espouses the philosophy of hating your enemy. People need to see the virtues of Christ witnessed through our lives, bound up in love. True love is not forced and it is not fake:
Don't just pretend to love others. Really love them. Hate what is wrong. Hold tightly to what is good. Love each other with genuine affection, and take delight in honoring each other. Romans 12: 9-10 (NLT)
People are too accustomed to the false love the world offers to not see it for what it is. We cannot approach the witness for Christ with anything less then authenticity. The virtues of God must be put on but without love binding them together in perfect unity, they will fall off. Kindness without love is shallow and short lived. It becomes an act instead of a way of life. It has no endurance. Humility without love is a lie. It is transparent. The same will go for every virtue of God. We do not easily choose to be gentle or forgiving it simply is not in the nature of man. The driving force then must be love. As verse 14 states, it is "over" all the other virtues. It binds them. It gives them unity. It solidifies our witness for Christ. That is how they will know Him. That is how they will see Him!