We were created by God.
That God is love, total goodness and the source of life.
That out of love, He created the entire universe.
Out of love, God gave us free will.
That we ought to behave a certain way, but we do not. We sin.
Because of our sin, we have severed ourselves from the life source, and now a great rift/schism/divide naturally exists between us, as there cannot be life without God.
Because there is no life without God, there is death. Suffering, chaos, turmoil and destruction all exist because of the evil and hate in the world.
But because of his relentless love for us, God does not want us to die. He wants to live forever with us. He does not want us to die.
So in the ultimate salvific act, God became a man - the historical person of Jesus Christ - to demonstrate his incredible love for us by being tortured and crucified and dying - all to save us. He forgave us for everything and resurrected from the dead, destroying death, making it possible for us to be resurrected too. He saved us from the death we brought upon ourselves.
We believe that after we die, we and everyone who has ever lived will be resurrected from the dead, and the entire cosmos will be renewed where we will live eternally in the full presence of God.
Thus, our time on Earth is a preparation for the day we face Christ. To slowly deify ourselves. To grow closer to God. This process is called Theosis. To be fully in his presence, we need to be prepared, otherwise the penetrating brightness of his holiness and goodness and love will be painfully blinding and will be torment for us. If we are prepared, this light will be heaven.