Because these are different points of view on behavior, on morality. When people of different religions collide, they may try to convert another person to their faith, condemn his religion, disagree with its norms. At the same time, believers defend their faith quite strongly, because it is part of their life, their spiritual world. Based on this, conflicts can arise. Therefore, yes, tolerance is needed. To avoid conflicts, you need to accept and respect the faith of another person, his choice, not try to convert or condemn his faith.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.