Many people are corpses while they are breathing. We can be dead two different ways: physically or relationally. Before we became Christians we were relationally dead to God. Even though we were relationally dead, God could see through our blindness and ignorance about him to see a person he loves. In fact, Ephesians tells us that he greatly loves us.
But God, being rich in mercy, because of His great love with which He loved us,
5 even when we were corpses in our transgressions, made us alive together with Christ (by grace you have been permanently saved), (Eph 2:4-5).
The amazing thing is that even though we were walking dead people, God made us alive together with Christ. That means Christ's life came into our lives and granted us a relationship to the Father such as the Son has. This was done not because of anything we did, but because of God the Father's great love. In fact, the last phrase in Greek says by grace you have been permanently saved.