Complex sentence: EMU had gained prominence as a result of their opposition to gay ordination in the lead up to the 1997 Assembly, however while gay ordination was the catalyst in forming this group, EMU focused on the issue of Biblical authority.
Split into simpler sentences: EMU had gained prominence as a result of their opposition to gay ordination in the lead up to the 1997 Assembly. While gay ordination was the catalyst in forming this group, EMU focused on fundamental issue was one of Biblical authority.