Bel was a term of respect in the Babylonian/Mesopotamian language, and Ba’al in the similar Hebrew, like my lord in English. Therefore they used to address their chief god as Bel Marduk, just as Christians talk about the Lord Jesus.
https://en.wikipedia.org/wiki/Bel_(mythology)
If you think it’s so terrible that they’re trying to restore ancient monuments, just because they were polytheists, you have the same mentality as ISIL.