The Lutheran confession of faith is that God is Three Persons and one Divine Essence. But then, what is man’s relationship with this God?
Lutherans confess that since the fall of Adam, ever person that is born in the natural way is born with sin. This means that the natural state of mankind is without fear of God, without trust in God, and with an inclination to sin.
This inclination to sin is called concupiscence. It means that man is not an inherently good person who occasionally sins, but is a person who inherently desires evil over and against the will of God. It is a disease, an original vice whose consequence is eternal death.
We deny that there is any power within man to effect His own salvation. This original sin is truly sin. If there were something within man, some reason or strength, to make him right before God, then the Christ’s glory and merits are obscured and unnecessary.
The only solution to this disease is the new birth of Baptism and the Holy Spirit. Baptism is the application of the Divine Name of God—Father, Son, and Holy Spirit—with water. It is a new birth from above, a true washing of regeneration.