What did William Miller believe the cleansing of the sanctuary referred to?

William Miller, a key figure in the 19th-century Adventist movement, interpreted the cleansing of the sanctuary as the purification of the heavenly temple. In his understanding, which was rooted in a particular interpretation of biblical prophecy, this cleansing involved a significant event that marked the beginning of a prophetic countdown leading to the second coming of Christ.

Miller's belief hinged on the interpretation of passages in the book of Daniel, particularly the 2300 days prophecy, which he believed pointed to Christ's ministry in the heavenly sanctuary rather than a physical event on Earth or within the Jewish temple. Miller argued that this process of cleansing involved a heavenly judgment and was necessary before Christ's return. His emphasis was on the "heavenly temple" rather than any earthly restoration or revival.

This understanding of the cleansing of the sanctuary as a purification process reflects the broader Adventist focus on the investigative judgment, which posits that Christ began a new phase of ministry in the heavenly sanctuary around the year 1844. Therefore, this interpretation aligns closely with Miller's teachings and the foundational beliefs of the Adventist movement.