So a comment in one of my previous posts stated that someone on TV implied that you cannot sin against man only against God. I do not know the context of what the TV said but we can indeed sin against man and in the ultimate end, when we do we sin against God. Genesis tells us that: 26 Then God said, "Let Us make man in Our image, according to Our likeness; let them have dominion over the fish of the sea, over the birds of the air, and over the cattle, over all the earth and over every creeping thing that creeps on the earth." 27 So God created man in His own image; in the image of God He created him; male and female He created them. Gen 1:26-27 (NKJV)
So we are image bearers of God. We were created to worship, praise, glorify, and fellowship with God. We are to reflect His glory by our behavior. I know from a theological point that there is probably way more to that but this is part of it. So we need to think of each other as image-bearers of God and the logical conclusion is when you slander, gossip, or in some way injure another, you have sinned against that person and ultimately against God. Jesus tells us that we are to love each other as we love ourselves. He also tells us that: 21"You have heard that it was said to those of old, 'You shall not murder,and whoever murders will be in danger of the judgment.'22But I say to you that whoever is angry with his brother without a causeshall be in danger of the judgment. And whoever says to his brother, 'Raca!' shall be in danger of the council. But whoever says, 'You fool!' shall be in danger of hell fire.
Matt 5:21-22 (NKJV)
Since hell is reserved for the unrepentent sinner, if you sin against your brother even if it is just calling hin a fool, you have sinned against God. Think like the image bearers we are.