Abraham lincoln said, "i hope to have god on my side, but i must have kentucky." what did he mean by this?

Abraham Lincoln himself was on a personal level against slavery, but as president he had to be very careful how to act on that belief. He was the President of a nation so he couldn't not act rashly. The slavery at the time was still legal in Kentucky and he could not risk Kentucky seceding so it was important to keep the borders intact.  This is why Lincoln did not issue the Emancipation Proclamation sooner. That is what he meant with this statement as he hoped God would be on his side but to win the war he had to have Kentucky as a part of the Union. 

Political forces often influence public opinion.