John 13:34, 35 (NKJV)
There are some things that are easy to identify because of how they look or sound. For example, a cow and a chicken look and sound very different; I doubt that anyone has ever gotten those animals mixed up. Another example would be a small car and a semi-truck, they look and sound very different. We are able to identify these things because of the distinctive look and sound that they have. But wouldn't it be strange for a cow to cluck like a chicken and a chicken to moo like a cow? And imagine the confused looks on people's faces if a small car would drive by sounding like a huge truck.
When Jesus was on the earth He showed love for His disciples, even though they argued about who was the greatest, misunderstood His intentions, and did not always do things the way He wanted them to. John 13:1 says that Jesus loved His disciples to the end. Then, in John 13:34, 35, Jesus told His disciples to love each other the way that He had loved them. Jesus went on to say that people would recognize His disciples because of the love they showed to each other. The love shown between those who follow Jesus should be an easy way for people to identify who they are.
Jesus performed miracles, did amazing teaching, and had a great prayer life, but Jesus never said these things would be the identifying traits of His disciples. In this context Jesus was specifically talking about those who followed Him, Jesus was not talking about our relationship to everyone but to fellow believers. If Christians demonstrated the kind of love that Jesus was talking about a lot of people would be very interested in joining that group to get some of the love. Our goal should be to walk in love with one another, to love like Jesus loved, and to be the example that Jesus intended us to be.