Believing in the name of Jesus Christ really doesn't take that much if we think about it. Believing in the name, quite simply, means that we believe in the Person of Jesus Christ. We believe that He is truly the Son of God and that He came to rescue us from the bondage of sin. We believe that He is the anointed one, the Messiah. In believing these things, we accept as truth, all of the teachings that He gave us.
But there is more to this verse than the line quoted in the title of this piece. The rest of the verse challenges us to "love one another, just as he has commanded us." (1 Jn 3: 23) Loving those who we close to us is quite easy. This demands nothing from us and there is no redeeming quality in this. (cf Mt 16:26, Mk 8:36, Lk 9: 25) Where the real challenge comes in is when we are expected to love those with whom we have problems or those who have hurt us or violated us in any way.
How do we go about loving those whom we perceive as our enemies? It is not easy. It is within our nature to at the very least avoid those who have hurt us. We run from them when we see them coming. It is built into our DNA to preserve ourselves at any cost. There are times when it is necessary to defend ourselves from harm. But we must also have the willingness to reach out to those who have not treated us very well to, at the very least, forgive them. Jesus Himself demonstrated this while He was suffering on the cross. "Father forgive them; for they know not what they do." (Lk 23: 34)
This is the difficulty of Christianity. In the past there has been much bloodshed prompted by those who professed to be Christians. They wielded the word of God as a sword, destroying enemies and people all in the name of the Lord. But Jesus from the cross tells us that we are to conduct ourselves differently. With one word he could have easily brought down the Roman executioners and released Himself from the cross in a triumphant display of power. That is what most people expected the Messiah to do. However, Christ's way was the way of humility.
It takes a great deal of humility to forgive. When we forgive, we swallow our pride. We recognize that the need for mercy is far greater than the need for vengeance and retribution. When we forgive we elevate the transgressor along with ourselves. We seek peace and offer to work to maintain that peace. We may be persecuted or ridiculed for our actions because our society calls for vengeance. It is more in a mode of an eye for an eye than love one another. As Christians, we must counter this by living the Gospel of Jesus Christ. We must be willing to call from our lives as Christ called from the cross, "Father for give them; for they know now what they do."