What should I do if someone at the church offends me?

I'm not sure what kind of offense you're experiencing, but our eyes must always be fixed on Jesus Christ. We do not fix our eyes on any Christian pastor or leader because they may offend you one day. And even if someone offends you, continue to grow in the Lord. Finally, when judgment day arrives, you will be held accountable to God Himself someday along with that individual. Personally, I will never waste my years of devotion to the Lord simply because of this person who upset me. Regardless of what that individual did to me, I will continue to pursue spiritual growth. Remember, the enemy takes advantage of this situation to prevent you from growing in Christ. The only way to progress spiritually is to ignore this type of offense. Some will say that this is difficult, but let's choose to obey God's word by learning to forgive. If that person does not know how to respond appropriately, do not follow his lead. Furthermore, have you considered the possibility that the Lord is using this as a test for you?  

A person with good sense is patient, and it is to his credit that he overlooks an offense. - Prov. 19:11

Keep your mind clear, and be alert. Your opponent the devil is prowling around like a roaring lion as he looks for someone to devour. - 1 Pet. 5:8

Let your eyes look straight ahead and your sight be focused in front of you. Carefully walk a straight path, and all your ways will be secure. Do not lean to the right or to the left. Walk away from evil. - Prov. 4:25-27

We must focus on Jesus, the source and goal of our faith. He saw the joy ahead of him, so he endured death on the cross and ignored the disgrace it brought him. Then he received the highest position in heaven, the one next to the throne of God. - Heb. 12:2