Life on earth is an opportunity for soul development. It takes many trips to earth or incarnations for a soul to grow fully. We've all lived many previous lives.
Reincarnation is the path to soul development.
Each soul helps choose the particular circumstances of incarnation in order to maximize individual growth potential. Wisdom is gained both by study and through actions. We all have the potential to become one with God. You reap what you sow, in this life and future lives. Karma is the law of the universe.