In this passage from his Second Inaugural Address, Abraham Lincoln is conveying the idea that God allowed slavery to exist as part of a divine plan or providence, and that the Civil War is a consequence or punishment for the sins associated with slavery. He suggests that the war serves as a woe due to the offense of slavery, indicating that it is part of a divine purpose to ultimately remove that institution from the nation. Therefore, the statement that best captures Lincoln's meaning is:
That the Civil War was a punishment from God for allowing slavery to exist.