The "mystery of iniquity" in Paul's time, and since his day, did not, and does not, consist in making too much of God's ordinances in their purity and proper use.

That cannot be done, any more than you can intelligently love the Bible too much, or the Sabbath.

But, to pervert them, or to make additions to them, or to rely upon them wholly, is Romanism.

But can men make too much of having a seal on a deed?
Is the deed good for anything without the seal?
Can they make too much of having three witnesses to their wills?
Those three witnesses, instead of two, make an otherwise worthless writing, a man's last will and testament.

Thus, a true sign, ordinance, or seal, among men, has inherent efficacy of some sort.