“You are a liar if you say you love God and you don’t love your neighbour”—Who says this and why?

Answer:  St. John, one of the twelve apostles says this. 

             According to St. John, if a man claims that he loves God very much and on the other hand he does not love his neighbour, that man is a liar. St. John gives reason behind this. He says how a man can love God whom he does not see or does not touch when he hates his neighbour with whom he deals in, lives, speaks. Thus St. John expresses his doubt in men about their fake love for God and wants everyone to love each other as God loves each of us.