I hope you will keep on believing what the Bible says, because it will make all the difference to you in the years ahead.
Let me explain. If God didn't put us here, then we are here by accident, and therefore our lives don't have any real purpose or meaning. Nor are we accountable to God for the way we live; if He didn't put us here, we can live any way we want to, no matter how selfish or hurtful we are. Like the writer of Ecclesiastes before he met God, we'll end up saying, "I have seen all the things that are done under the sun; all of them are meaningless, a chasing after the wind" (Ecclesiastes 1:14).
But the Bible says God created us and put us here -- and that makes all the difference. It means we have a reason for being here: to know God and do His will. It also means we can know how we should live, because God has told us what is right and what is wrong. Most of all, it means we can know Him in a personal way, because He came down to earth in the person of His Son, Jesus Christ, to bring us back to Himself.
Respect those like your teacher who look at life differently -- but don't be misled by them or assume their views are right. Instead, commit your life to Jesus Christ and build your life on Him. He alone could say, "I am the way and the truth and the life" (John 14:6).