Perhaps this is by far the hardest commandments Jesus gives (yet it was a spiritual gift to the early church). It is not only good enough to love one another, but we place too much of our own love on converting one another to our own faith, our own moral high ground if you would. In fact I believe most wars fought between catholic and protestants, and division in our country stems from ignoring the core principal, love your neighbor. Not love your brother. It says in this scripture, pray for those who persecute you, but first I would elude to the fact that we can not pray for our neighbors if we do not ask first to be given this gift of love. Or even if we feel the urge to, our flesh wars with our spirit thus the need to ask the spirit to win that battle. Thus the saying you have not because you do not ask. I was told once, fix the hand shake to fix the man. I thought it odd but it lasted with me. We all have fault within ourselves, and we need to fix ourselves (not us doing that work literally, because we lack the capacity). If we would follow this one commandment, I believe the world would be asking what gives you that shine. In the face of what you call a time of sin abounding (in a better context, sin is to the father and follower of christ, offensive or offends our soul as we follow him), your ability to shake hands with anyone who does not profess faith, that is what makes a unbelieving world see and say I want that. Or it doesn’t, and they see your love in the face of it. If there is only love for the brothers, then you no different than the world, and if you are not different than the world then you create occasion for separation from the father. It is good to love that which is good, but we still must love those who don’t do right according to what we know to come from the father, the son and his spirit.
Matthew 5:43-48 ESV
“You have heard that it was said, ‘You shall love your neighbor and hate your enemy.’  But I say to you, Love your enemies and pray for those who persecute you,  so that you may be sons of your Father who is in heaven. For he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust.  For if you love those who love you, what reward do you have? Do not even the tax collectors do the same?  And if you greet only your brothers, what more are you doing than others? Do not even the Gentiles do the same?  You therefore must be perfect, as your heavenly Father is perfect..