I'm pleased to hear your pastor has seen the light on this topic. Except for a visiting children's choir for South Korea, we have not had anyone sing that one since our new pastor arrived in 2000. A year or two earlier, several members walked out during a performance of Copeland's "Lincoln Portrait" during a 4th of July service --
http://www.lincolndouglasquincydebate.com/html/a_lincoln_portrait.html

Objections to having BHOR played in most churches are based on three points --

1) As a devout Unitarian, Julia Ward Howe believed Christ lived an exemplary life, but certainly was not the Son of God. In her opinion, Jesus was nothing more than another mortal like the rest of us. In most churches that alone would be enough to scratch this song.
2) Julia Ward Howe wrote the song to memorialize John Brown, the famous religious terrorist who was executed by the State of Virginia in 1859. She and other admirers of John Brown stated that as Christ had hallowed the cross, Brown's death would glorify the gallows. I'm certain that her "terrible swift sword" is an allusion to swords Brown used to murder Southerners in Kansas in 1856.
3) A few Christian hymns use a militaristic analogies -- "Onward Christian Soldiers", for example. However, "Battle Hymn of the Republic" is the only 'hymn' I can recall which celebrates the destruction and defeat of one group of people by another. The appropriate response to these situations is found in Joshua 5:13 --

"Now when Joshua was near Jericho, he looked up and saw a man standing in front of him with a drawn sword in his hand. Joshua went up to him and asked, 'Are you for us or for our enemies?' 'Neither,' he replied, 'but as commander of the army of the LORD I have now come.'"

Jim, I'm way off topic here and would not object if you moved this post to "News and Views" where it properly belongs ---

Julia Ward Howe