Any Temple or animal sacrifice will be an abomination to God.
"He that killeth an ox is as if he slew a man; he that sacrificeth a lamb, as if he cut off a dog's neck; he that offereth an oblation, as if he offered swine's blood; he that burneth incense, as if he blessed an idol. Yea, they have chosen their own ways, and their soul delighteth in their abominations". (Isaiah 66:3)
A recent article begins with the words, “Last Tuesday, the Temple Institute’s Red Heifer program was blessed with results; an entirely red female calf was born, paving the way for re-establishing the Temple service and marking the final stage of redemption”. This event has been picked up by newspapers world-wide with such lurid headlines as, “First ‘red heifer’ born in Israel for 2000 years triggers Armageddon fears” and “End of the World fears: First red heifer ‘born in Israel in 2,000 years fulfils prophecy’.” Secular Jews have gone on record as wishing the young cow would just disappear; some have even suggested that it be destroyed to avoid a potential war. This may seem an over-reaction but Rabbi Moshe ben Maimon (Maimonides), the most renowned medieval Jewish scholar known by the acronym Rambam, wrote in his explanation of the mitzvah that “the tenth red heifer will be accomplished by the king, the Messiah; may he be revealed speedily, Amen, May it be God’s will.”
The “red heifer” that has recently been born and certified “unblemished” is the tenth one, and the first red heifer since the destruction of the temple in AD 70. This is a powerful sign for “third temple fanatics” as rebuilding the third temple is closely linked with the appearance of the Messiah and the third temple cannot be built unless there is a way to cleanse the priesthood. That is why they require the Red Heifer.