In Noah's day, GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. And it repented the LORD that he had made man on the earth, and it grieved him at his heart. Although Noah lived in a very sinful time, he maintained his relationship with God. The Lord would not destroy Noah because of his righteous life, in this time of judgement upon the earth God extended his everlasting mercy to Noah. Jesus taught that if extend mercy to others we will be blessed by receiving mercy ourselves.
Mercy involves tolerance, understanding and forgiveness.
To be merciful involves showing Christian kindness, having a forgiving heart, and being willing to love rather than to hate. Being merciful to others means going the extra mile, giving another handshake, offering another smile, and being willing to pray another prayer. When we extend mercy we can expect to recieve mercy from others. All men would stand guilty before God if it was not for his mercy. God does not refuse to love, show compassion, or forgive and neither should we.