The Heading above states that in the individual details in the Word there is a marriage between the Lord and the church and therefore a marriage between goodness and truth, because wherever there there is a marriage between the Lord and the church a marriage between goodness and truth is also present, since the latter marriage comes from the former one.
When a whole church, or just an individual within a church, has truths, the Lord flows into these truths with goodness and brings them to life. To put it another way, when people who are part of a church understand something true, the Lord flows into their intellect and enlivens it by bringing goodwill into it.
We all have two faculties of life called the intellect and the will. Our intellect is a vessel for truths and therefore for wisdom; our will is a vessel for goodness and therefore for goodwill. For us to become part of the church, these two parts of us have become one. The two parts do in fact become one when we build our intellect with genuine truths (which happens to all appearance as if we were doing the building ourselves) and our will is filled with goodness and love (which is done by the Lord). Then the life of truth and the life of goodness are in us–the life truth in our intellect and the life of goodness in our will. When these two lives are united, they become one life, not two. This is the marriage between the Lord and the church; it is also the marriage between goodness and truth in us.
from True Christianity, Volume 1, Section 249