Why would God command John to measure something as vast and sacred as His temple? This wasn't about architectural plans, but about divine protection.
The act of measuring in ancient times often signified claiming ownership, setting boundaries, and preparing for protection or even preservation. Think of a landowner marking their property lines.
In Revelation 11:1, John is given a measuring rod, not to physically measure the Jerusalem Temple (which was in ruins or about to be), but to symbolically mark out God's true dwelling place and His people. This measurement is a divine declaration: 'This belongs to God, and it will be preserved.' It's a sign that even amidst impending judgment and desolation, God's faithful are set apart and protected by Him.
This concept echoes the sealing of God's servants in Revelation 7, another act of marking for preservation amidst judgment. God's measurement is His promise of security for His own.