Actually, Scripture acknowledges that the "silent witness" approach has its place, but it's in the context of a Christian woman submitting to her unbelieving husband.
Likewise, wives, be subject to your own husbands, so that even if some do not obey the word, they may be won without a word by the conduct of their wives, 2 when they see your respectful and pure conduct. 3 Do not let your adorning be external—the braiding of hair and the putting on of gold jewelry, or the clothing you wear— 4 but let your adorning be the hidden person of the heart with the imperishable beauty of a gentle and quiet spirit, which in God's sight is very precious. 5 For this is how the holy women who hoped in God used to adorn themselves, by submitting to their own husbands, 6 as Sarah obeyed Abraham, calling him lord. And you are her children, if you do good and do not fear anything that is frightening. ~~1 Peter 3:1-6 (ESV)
Somehow, I rather doubt the young woman in the following video had such self-sacrificial behavior in mind when she reproved the street evangelist for proclaiming that humanity is fallen and desperately needs a Savior. Sweet, non-confrontational evangelism keeps us comfortable, I'll agree. But who can understand the good news of Jesus atoning for his or her sin until he or she recognizes that every human being desperately needs salvation? In fact, Jesus showed people that they were hopelessly locked in sin, just because they belonged to the human race. His sermons required people to see the filth in their hearts so they they would understand their need for His mercy.
And His mercy soothes my heart precisely because He's allowed me to see how thoroughly wicked I am apart from Him. I see His kindness in accepting God's wrath as He hung on the cross shedding His innocent blood to pay the penalty for my sin. He even declares me to be righteous on account of His death on the cross!
Without a truthful view of how wretched I am apart from Jesus, how could I begin to appreciate the wonderful grace He gives? And how could anyone else appreciate His mercy toward him or her? Proclaiming the bad news of human depravity hurts both the listener and the person delivering the bad news. But unless people hear it, the Gospel really isn't Good News.