John 3:14-17, part of Jesus' nighttime discourse with Nicodemus, forms the basis of this song and includes that famous profession of faith "God so loved the world. . . ," one of the best-known and most frequently memorized verses in the entire Bible. In this setting that profession is used virtually as a refrain but is numbered as stanzas 2 and 4 for emphasis.
Bert Polman, Psalter Hymnal Handbook
The Catechism says that those who know Christ’s forgiveness are “to thank God for such deliverance” (Heidelberg Catechism, Lord’s Day 1, Question and Answer 2). As a result, “With our whole lives we may show that we are thankful to God for his benefits, so that he may be praised through us, and that we may be assured of our faith by its fruits, and so that by our godly living our neighbors may be won over to Christ” (Heidelberg Catechism, Lord’s Day 32, Question and Answer 86).