|God promises are true - He is faithful.|
Satan tricked Eve to disobey God and to become unholy therefore unable to stay in God's presence. Eve led Adam, and in turn Adam's children from that point on continued to be cursed by disobedience.
God did everything for us. There is no thing we can do or that we need to do . It is already done! All we need to do is believe God.
There it is - you have read the Gospel - plain and simple. If you believe, you can read on to see what you must do.