Rob Dalrymple, «The Use of ka1/ in Revelation 11,1 and the Implications for the Identification of the Temple, the Altar, and the Worshippers», Vol. 87 (2006) 387-294
Thus, by means of the symbolic act of measuring ‘the temple’, which is composed of those who will suffer martyrdom (‘the altar’) and those who remain faithful to the end (‘the worshippers’) John reassures the entire covenant community that their eternal destiny is firmly within the sovereign judge’s control. The epexegetical use of ka1/ in 11,1b explains why it is ‘the altar’ and not some other piece of furniture that is measured. Finally, the distinction between the righteous who are martyred and those who are not confirms that John did not perceive all of the righteous as suffering martyrdom.