In an atmosphere of worship/praise and a belief in Christ alone, all of the world's differences in theology melt away. I get that...and it's nice to be able to just worship together.
However, wrong theology can still mess that up at times. People may love a song they heard from long ago and enjoy singing and using it for worship but they sometimes don't really give much thought to the words. For an example someone asked our choir to sing a song that was in Latin (which none of us could read/understand very well) but when researched it gave praise and glory to the virgin Mary. I sure don't want to worship Mary, even though I have great respect for her. Keeping good theology even in our music allows our worship/praise to be pure of idolatry or from being too sensual. Sometimes I think that is why some churches use a lot of repetitive "safe" phrases that everyone can agree on.
Asking God to fill me, does not sound unbiblical to me. It did sound like MacArthur had his mind in the wrong place about that repetitive phrase...but we didn't hear the whole conversation either. Hopefully Dr. Brown did hear it and was able to have a balanced understanding of what was said and not just based on sound clips.