1 Corinthians 13:4-7 -- "Love is patient and kind. Love is not jealous or boastful or proud or rude. It does not demand its own way. It is not irritable, and it keeps no record of being wronged. It does not rejoice about injustice but rejoices whenever the truth wins out. Love never gives up, never loses faith, is always hopeful, and endures through every circumstance."
These familiar "Be Attitudes" are the description God gives us for agape -- the unconditional love God has for us, His children. This is the kind of love we should strive for in our quest to be more like Christ. To experience agape loves doesn't mean that what I do bothers you and you chose to be kind and not react, it means that my nuiances don't bother you in the first place.
As you have guessed, this is not easily accomplished by humans on earth. There is too much sin and too much evil to wade through for this form of love, agape, to ever succeed on earth. However, God know that, which is why He sent Jesus to teach us and save us from sin. Once Jesus conquers sin once and for all -- agape is the only form of love we will know.
When John encourages us to love each other, he is speaking of the agape form of love that comes only from God. He is encouraging us to put our differences aside and lift each other up with patience and kindness, and to put other in front of our own needs and desires. Only by taking ourselves out of the focus can we love others the way God intended us too.
Let's face it -- this is our ideal, this is God's love for us. If you reach this kind of love even to those closes to you, much less strangers, then you are a miracle. The point is we are always working for the perfect love towards all people. When you fall short, repent to God and ask Him to guide you in how to continue to love others. God will guide you because He knows all about love. Anyone who loves and constantly tries to love knows God. God is love.