Infections are caused by infectious agents such as viruses and bacteria. God who is goodness itself has been endlessly hurt in His heart whenever His creature mankind has sinned. But He did not even spare His only begotten Son to redeem us from our sins. Although we receive such grace, if we get hot-tempered and do not forgive others, God said that He also would not forgive our wrongdoings (Matthew 18:35). Thus, forgiveness is not for others but for yourselves. It is for your happiness.