"For this is the message which you have heard from the beginning, that we should love one another; not as Cain, who was of the evil one and slew his brother. And for what reason did he slay him? Because his deeds were evil, and his brother's were righteous. Do not be surprised, brethren, if the world hates you. (1 John 3:11-13)The kind of love that John is calling us to have for one another is the kind that is expressed in deeds. John is not talking about affection or a warm fuzzy feeling but rather love that expresses itself in good towards another. The kind of love that acts not just feels. In speaking of Cain who was evil (or wicked) John uses a particular Greek word that indicates someone's hurtful and grievous acts rather than the character or nature of their heart. It is a wickedness that expressed outwardly rather than merely being born inwardly. Similarly, in contrast, our love ought to be outwardly not merely felt internally in our hearts. This is the kind of love that we, as children of the One who is love, are called to have.
This command is nothing new. The Law taught us, "If there is a poor man with you, one of your brothers, in any of your towns in your land which the Lord your God is giving you, you shall not harden your heart, nor close your hand from your poor brother; but you shall freely open your hand to him, and shall generously lend him sufficient for his need in whatever he lacks." (Deuteronomy 15:7-8) Singularly, Paul encourages us, "So then, while we have opportunity, let us do good to all people, and especially to those who are of the household of the faith." (Galatians 6:10) While we are saved without works of the law, we are not meant to live without works of faith. As children of God we are called to good works; to doing good to those around us; to sharing God's love through everyday actions and deeds done in faith and motivated by love. After all, as John will later put it, "But whoever has the world's goods, and sees his brother in need and closes his heart against him, how does the love of God abide in him?" (1 John 3:17)
However, though we are called to love one another, we must not presume or expect to be universally loved by all. Jesus has called us to love everyone not to be loved by everyone. No one minds a Christian who keeps their faith as private and personal. However, the world recoils at a believer who dares to live the faith they profess. When we live Godly lives and show forth the love of God through our deeds then we set a standard for the world, a standard of righteousness that the world is incapable of apart from union with Christ. For some, this contrast will be a beacon of hope drawing them into relationship with God's Christ, but for others, it will convict them of their own wickedness they wish to keep hidden. For these, their hate will be directed at that which exposes their own need and failures. Jesus said, "This is the judgment, that the Light has come into the world, and men loved the darkness rather than the Light, for their deeds were evil. For everyone who does evil hates the Light, and does not come to the Light for fear that his deeds will be exposed. But he who practices the truth comes to the Light, so that his deeds may be manifested as having been wrought in God." (John 3:19-21)
It is natural to want to be loved by everyone but it is a trap and a snare to expect it. We must live our lives in the light of God's love, sharing that love with the world around us, and not be surprised if some might take offense. Their offense is their portion but the love of God is ours.