This Earth is a test, a battlefield, for all living beings.
We were not designed as perfect beings, and after eating the forbidden fruit, we only fell further. Our inherent proclivities render us imperfect, so we are put into an imperfect world.
Why does God allow us to suffer? Because we were designed to be imperfect, but being exposed to objective perfection we are granted free will, giving us the choice to cling to our imperfections or to seek something greater.
Suffering allows us to grow, to mature, to learn, and to appreciate the good. While balance exists, it is important to align yourself with positivity, so that your influence and consequent influences will be positive. It is this positivity with the false and evil that create the battlefield on this planet.
There are many strategies for fighting, but the only winning one is positivity as defined by God. All others are flawed and cause unnecessary suffering, even on an earthly level.
In aligning yourself with positivity, you are preparing yourself for the next world. If you align yourself with this world [meaning, Earth], you will not be ready or fitting for Heaven. Many, many chances are being given to man to change, and to adopt the ways of the place they are going, rather than the place where they are.
Salvation is not simply outward changes; it is a complete transformation of self into a being preparing for Heaven and seeing beyond the ways of Earth. One day, you will leave the battlefield and return home. But where is your home going to be when you lay down your gun?