Scripture is written by people. Inspired scripture is written by people under God's inspiration. Inspired scripture is inherently deeper than that which is not. The Church has recognized this point, and discerned three spiritual senses of interpretation (allegorical, moral and anagogical) of the canon of scripture to supplement the literal interpretation. To tease out the literal interpretation, it can be necessary to apply technical means such as historical and literary criticism. What did the original human author intend to convey?
It is the techniques used to tease out the literal interpretation of scripture that are appropriate for interpretation of the U.S. Constitution (or any historic constitution, for that matter). Spiritual senses of interpretation are inherently specious, because the actual text cannot be said to be scripture, per se. It has no meaning beyond the literal.
This does not prevent progressive (or, if you prefer, activist) jurists from employing "spiritual" interpretation methods to uncover the hidden meaning of the Constitution and its amendments. Such "spiritual" interpretation is primarily, I suggest "anagogical". What does that mean, you ask? It means that progressives see an end of history (an eschatology, if you will) toward which the Constitution was aimed, and they are simply setting themselves up as a magisterium empowered to discern what that end is, and how the Constitution points toward it.
Doing so, of course, amounts to an admission that some deity is directing the process. The question that arises in my mind is "what deity"? Since a number of the features of the progressive eschatology contradict what is plainly laid out in the canon of scripture, I think it can be safely claimed that the progressive deity is not God.