Yes, I think that you can disagree with a pastor and continue to support him. However, it depends what the disagreements are about. You will have to determine whether or not the areas of disagreement are important enough to keep you from being able to support him.
One of the big issues will be the direction of the church. I may disagree with an opinion that the pastor has. However, if I disagree with the total direction in which he is taking the church, then for my sake, and his, I need to get out. An individual will have to determine how much disagreement he can tolerate with a pastor's teaching. For example, I personally couldn't function under a man who doesn't use the KJV. I would not want to be part of a church where the pastor brought in speakers who didn't use the KJV. However, I also believe in the local church, but I could continue to function in a church where the pastor had in speakers who occasionally referred to the universal church. If it was being crammed down our throats, then I would have to leave. In addition, the Bible teaches that there are areas where good Christians can disagree (Romans 14).
Perhaps this would be a good measuring stick - if I could not, in good conscience, bring the lost, or a baby Christian, to the services in my church out of fear for what might be said or done during the service, then I need to get out.
Let me add this - if you are going to be miserable in your church, then you should leave. The Bible says that "I was glad when they said unto me, let us go into the house of the Lord." If you are trying to please God, and live a Biblical life (in other words, your problem isn't that you are backslidden), and yet you are not glad to go into the church, then that might be a hint that you need to find another church to attend.
Pastor Dr. Mark Montgomery
Ambassador Baptist Church
1926 Babcock Blvd
Pittsburgh, PA 15209