@HMTM
You are confusing the political parts of lincolns letter with his own wishes. I suggest you re read it. He specifically states that it is his "oft expressed wish" that all men everywhere be free. The part that was politics is all the bits before that where he talked about the union and preservation of it. But his last point, the conclusion he chose to wrap it all up, was his personal expressed wishes that all men be free.
Further, the Emancipation Proclamation destroys your notion that it was merely political,
And by virtue of the power, and for the purpose aforesaid, I do order and declare that all persons held as slaves within said designated States, and parts of States, are, and henceforward shall be free; and that the Executive government of the United States, including the military and naval authorities thereof, will recognize and maintain the freedom of said persons.
And I hereby enjoin upon the people so declared to be free to abstain from all violence, unless in necessary self-defence; and I recommend to them that, in all cases when allowed, they labor faithfully for reasonable wages.
And I further declare and make known, that such persons of suitable condition, will be received into the armed service of the United States to garrison forts, positions, stations, and other places, and to man vessels of all sorts in said service.
And upon this act, sincerely believed to be an act of justice, warranted by the Constitution, upon military necessity, I invoke the considerate judgment of mankind, and the gracious favor of Almighty God.
I am more than willing to admit that religion has had some positive moral effects on society (though far less than bad). But in order for you to really make people believe that freeing the slaves was not a moral concern, you would have to (and apparently have) ignore Lincolns own words in the very letter you reference, as well as his claims of justice in the Proclamation and his deference to God, as well as convince them that these clear religious declarations are not moral in nature but instead political."Judgement of mankind"? Those are his words, do you think he believed their politics were being judged or their morals? Which is God more concerned with?