Sin always effects both vertical and horizontal relations.
John Calvin says somewhere that a preacher ought to be often in the third of Genesis, the third of John, and the third of Romans. In the third of John we read of the new birth, without which no one can see the kingdom of God. In the third of Romans we read of God's justification of sinners through the righteousness of Jesus Christ. In the third of Genesis, however, we read of the reason, the necessity for those other two chapters. The third of Genesis explains why there must be a new birth and why God must justify sinners.