Being A Christian doesn't mean we don't have the same problems as everyone else, but sometimes they matter more!
You sound like a normal family!
Give your children lots for praise when they do things well. Give rewards such as extra storytime, chance to play a game, do some cooking or go to the park, as they are valued more than sweets or extra money etc, and improve your relationships. Explain rather than get angry if you can when things go wrong. Health Visitors and School Nurses are good sources of parenting support and advice,and there are lots of good books in Christian bookshops.