1 Peter 1:22-23
Once we give our hearts and lives to Jesus, we SHOULD change. Not immediately or over night. It’s a process. We have mindsets to change, habits to break, and sin to stop. But God doesn't expect us to be a different person upon confession of faith. (We also will NEVER be perfect. The only perfect human is Jesus.) We should grow and learn about Him & His way of living. This includes how we treat people.
Our new life will last forever because we go to Heaven when we die. The goal here on earth is to take as many people with us as we can!