The Old Testament way of relating to God is not the same as the New Testament way of having a relationship with God. The Old Testament was all about fulfilling God’s laws and it was based on your performance. Under the Old Covenant, a sacrifice had to be offered every time a sin was committed.
But when God sent Jesus, The Old agreement with God was replaced with grace. It is based on accepting of what Jesus did. If you follow Jesus, you’ve become a new creature, and sin no longer needs to be a barrier between you and God.
Another name for the devil is ‘accuser’ – what do you feel accused of? How can we live in the promise that we will ‘taste and see that the Lord is good’?