One reason Christians disagree about some things, I'm sure, is because churches are made up of human beings and as long as we are on this earth, none of us will be perfect. Someone has said that if you ever found a perfect church, it would become imperfect the minute you joined it!
Another reason Christians sometimes disagree, however, is because the devil loves to see Christians disagree or be in conflict with each other. One of his goals is to discredit the Gospel and one of the ways he does this is by encouraging Christians to fight or appear foolish. They aren't deliberately serving Satan but he is always in the background, encouraging conflict and division. One of the sins God hates, the Bible says, is "a man who stirs up dissension among brothers" (Proverbs 6:19).
At the same time, don't be misled by disagreements you hear of from time to time. Yes, Christians may disagree on minor points but all believers are united on the essentials of the Gospel: that Jesus was God in human form, that He died on the cross for our sins and rose again for our salvation, that He will open heaven's door for us as we respond in faith to Him.
Most of all, don't let the disagreements of a few keep you away from Christ. God loves you, and He yearns for you to come to know Him in a personal way. Why not turn to Him and ask Him to come into your life today?