In the beginning God created everything and everyone, and it was very good. He created human beings to care for the world and to live in relationship with Him.
However, the first humans decided they didn't want God to rule their lives - they wanted to live their own way without them. God punished them and sent them away.
But God still loved humans. And so he planned to bring blessing to the whole world again. His plan would come about through a man called Abraham. God promised that he would have descendants, who would live in a land provided by God, and through them the whole world would be blessed.
Abraham had many descendants, but they ended up living in Egypt in slavery. This was not the land and blessed life God was talking about! The people cried out to God and he raised up Moses who led them out of Egypt.
Eventually they got to God's promised land, but instead of living a life obeying God and being blessed, they turned their backs on God and worshipped false gods instead.
The people asked for a king. God made a promise to one of the kings, David, that his family would always rule God's people. One day a king would come and bring the promised blessing to the whole world. This king was called 'the Messiah' or 'Christ'. The rest of the Old Testament is waiting for the arrival of the Messiah...