There are two basic answers to this question.
Atheists – that is, people who believe that there is no god or “higher power” – say that we are here by accident. The materials to make to planets and stars and animals and human beings were always present and somehow came together in a way that made life possible. There are different theories about how this “coming together” happened, but they all agree that it happened by itself, without plan or purpose or meaning.
Theists – people who believe in a god or higher power (members of world religions and Christianity are all theists), say that planets and people are not here by accident, but by the choice of a supreme being. They believe that God brought us here – created us – and for some reason. We are part of someone’s plan. Therefore, our lives have a special meaning and purpose.
At this point, do you believe that the earth and stars and all living things developed by accident or by the decision of a higher power? In other words, will you decide to be an atheist or a theist?