Maryland was not “split” in its views on the Civil War. It was a southern state. Most of the state had slaves. Many of Maryland’s prominent citizens owned slaves. Some of the ships built in Baltimore were used to transport slaves. It would have seceded if it had a choice. The first casualties prior to the start of the war were in Baltimore, where Union troops fired on citizens throwing bricks at them. The Union prevented the Maryland legislature from meeting (including a clandestine attempt to meet in Frederick) so that it could not vote to secede. There were a few Union supporters, but if the legislature had met it would have voted to leave.
Quite a few Maryland regiments fought for the South. There were some Union regiments also, but they were drafted. Maryland has a history of over a hundred lynchings of black people, quite a few after the war.
I’m not advocating for keeping our racist song. On top of its lyrics, I think “Oh Christmas Tree” is a stupid melody for a state song. But to pretend that Maryland was actually significantly divided on the concept of slavery or sympathy for the South during the Civil War seems to be an attempt to whitewash our history. We should be “woke” enough to admit that Maryland was part of the racist history of the United States. If we do change our state song, we should be putting a monument up listing our old song’s lyrics and the new ones to say to the world that yes, we were racists but now we reject that past.