Living the Christian life is not only difficult, it is impossible. And one of the main reasons it is impossible for us to live for Christ (in our power) is that we are fighting a spiritual war on two different fronts. We have our internal battle, our constant tug-of-war between our spirit being led by Christ and our flesh being led by our desires, because we were born with a sin nature. (Romans 7:17-24) We also live in a world that has been marginalized and diminished by the curse of our original sin which has resulted in the distortion of God's desire for this planet.
Then we have to factor in the presence, power, and influence of an ex-angel, who driven by selfish ambition, pursued his own agenda and rebelled against God. His rebellion resulted in not only his banishment from Heaven, but also of one-third of the angels that had lived in paradise before this choice. Now these fallen creatures have one goal, to steal, kill, and destroy as many humans for their cause as possible before their time runs out.