From what I know, since sin came into this world, suffering came with it. God gave us free will and it's our choice to make the right decision or not. God has a plan for people's lives that they may not always understand. This may include evil and suffering but Christians should trust and have faith in God's plan. Evil and suffering in this life is a preparation for heaven. Evil and suffering give people a chance to become better people and improve their souls. They believe that God will reward them in heaven.
Independent clause this is because they is the subject , know is the verb so simply is the adjective. all a sentence need to stand on its own is a noun and a verb :)your welcome