Ezra, who was sent to teach the scriptures to the exiles, spent his first stint in Jerusalem, separating families to purify the people rather than letting God deal with His people.
When we reconcile with our brethren, we receive a temporary peace, our peace of mind. But what Jesus offers us is much more. It is the ultimate peace in our hearts, knowing that our broken relationship with The Father has been fixed by His death on the cross.
Jesus goes on to say that what is the point of loving only those whom we like and that even the pagans do that. We have seen the love of God, the unconditional love that God has shown us.