“Now in these days when the disciples were increasing in number . . .” (Acts 6:1, ESV).
Let me just set the tone, the background for this passage of Scripture. It was in the very early days of the Church, probably just weeks or, at most, a few months after Pentecost, and the Church had seen explosive growth. Three thousand people had been saved in one day! They began to meet in homes and not only Jews but Gentiles were being saved. Also Samaritans and Ethiopians were becoming believers, so various cultures came together, cultures that were not used to being together at all. 
As a matter of fact, these new believers were very racially segregated and they did not like one another. They had persecuted one another, defamed one another, and now all of a sudden they found themselves flung together in the very same Body of Christ — saved, sanctified, filled with God’s Holy Spirit — working together. And it was going quite well. 
It was so strange. At Pentecost not only did people hear others speaking in their own language but now they were seeing people not of their own race, of their own gender, of their own nationality, of their own backgrounds, worshiping together, serving together, loving one another. This kind of love, Jesus said, is “the kind of love that will make the world know that you are My disciples. And this is the kind of love that will cause people to believe in Me.”
When we are doing the thing that we are called to do — reaching out to the lost — and doing it with this kind of love, serving one another with this kind of need-meeting mentality, then the world is going to be drawn and attracted to Him.
“By this all people will know that you are my disciples, if you have love for one another” (John 13:35, ESV).