If God brought your pastor to your church, then he is God's choice for that position, and he should be respected as long as God has him there. The Bible tells us "to respect those who work hard among you, who are over you in the Lord" (1 Thessalonians 5:12). Gossiping and backbiting will only hurt God's work in a church.
The most important thing you can do for your pastor is to pray for him–and encourage others to pray also. A praying church is a harmonious church–and the reason is because everyone is seeking God's will instead of their own. Prayer is essential in God's work, and most of all we should be praying regularly for our pastors. Paul's plea could be echoed by almost every pastor: "Finally, brothers, pray for us that the message of the Lord may spread rapidly and be honored" (2 Thessalonians 3:1).
Then encourage your pastor. Go out of your way to thank him for his sermons; remember his birthday or other special occasions; let him know you are praying for him. Encourage him also to strengthen his gifts and grow in his abilities. We all need encouragement, and your pastor is no exception.
Finally, ask God to help you be a peacemaker in your church, and urge others to do the same. The Bible says, "There is deceit in the hearts of those who plot evil, but joy for those who promote peace" (Proverbs 12:20).