A Saudi-led coalition force of 41 countries is now taking shape and has found a focus: protecting member nations against the threat from Islamic State as the militant group’s strongholds in Iraq and Syria disintegrate.

The coalition, sometimes referred to as the “Muslim NATO,” is expected to have its first substantive meeting over the next few months in Riyadh when defense ministers from member states, from Morocco to Malaysia, will gather to agree on its structure and mission.

However, these are Sunni-majority nations and absent from the alliance is Saudi Arabia’s major rival in the Middle East, Shiite powerhouse Iran, which sees the grouping as a sectarian show of force. […]