Second Inaugural Address

[Gene C]

It is confusing, mostly because of the language of the time, plus he is talking like a lawyer. This is how I understand what Lincoln says

If slavery is an offense to man and God, if God wills that slavery end now, and as a result the Civil War occurs (with all its terrible consequences) don't stop believing in all the good attributes we ascribe to God.

Don't blame God for the war, maybe God willed for slavery to end now, but the war is a consequence of man's actions. The consequences were going to have to be dealt with sooner or later. This doesn't mean that God is not good, he is the same yesterday, today and tomorrow.

Unrelated - In a country that had seen so much death, there was more of an emphasis and a concern placed on "life after death", than there seems to be today.
Without a good and loving God, "life after death" can not exist.