What does it mean that 'only he who now letteth will let'?

(by Daniel Peterson deseretnews.com 6-13-19)

Among the scriptural verses that Latter-day Saints often cite in order to explain their belief in a universal apostasy from the ancient Christian church is a passage that, in the King James Bible, is frankly rather obscure:

“For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way. And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming” (2 Thessalonians 2:7-8).

But what does it mean to say that “only he who now letteth will let, until he be taken out of the way”?
The problem in understanding those words derives from the complex history of the English verb “to let.” (Its association with “leases” and “letting” apartments is an entirely different subject.)

In common contemporary English usage, “to let” means “to permit” or “to allow.” We “let” a worker take a day off, for example. We “let” someone into our house, or “let” somebody “get away with it.”
This has evidently been a common use of the verb since the 10th century.

However, the verb “to let” has also been used since even earlier, in the ninth century, to mean exactly the opposite: “to hinder.” “By heaven,” says Shakespeare’s Prince Hamlet, drawing his sword when friends attempt to prevent him from following after what seems to be his father’s ghost (Hamlet I.iv.90), “I’ll make a ghost of him that lets me.” We might, today, misread this as “I’ll kill whoever permits me to do so,” but what he’s really saying is “I’ll kill whoever tries to stop me.”

This meaning of the term is rare in modern English, but it can still be found in certain contexts. The sometimes odd and archaic vocabulary of tennis, for instance, uses the word “let” when the tennis ball hits the net during a serve.

And in legal language, which often preserves Latin and other linguistic fossils, the term continues to be employed in this old sense. Since perhaps the 16th century, for example, people have been said to enjoy the use of a possession or of the right to vote “without let or hindrance.” (The phrase also occurs in Mark Twain’s 1881 novel “The Prince and the Pauper,” which deliberately seeks to employ archaic language appropriate to its setting in the mid-16th century.)

How is it possible that “to let” can mean both “to permit” and “to hinder”? The explanation is to be found in the word’s medieval roots. Our modern verb “to let” comes to us from two quite distinct Anglo-Saxon verbs: “laetan” meant “to permit,” while “lettan” meant “to prevent.” The fact that they both came to be spelled “let” is a confusing coincidence.

It is, however, in the second and more archaic of these meanings that the term is used in 2 Thessalonians, as is plainly illustrated in the Revised Standard Version translation:

“Now concerning the coming of our Lord Jesus Christ and our assembling to meet him, we beg you, brethren, not to be quickly shaken in mind or excited, either by spirit or by word, or by letter purporting to be from us, to the effect that the day of the Lord has come. Let no one deceive you in any way; for that day will not come, unless the rebellion comes first, and the man of lawlessness is revealed, the son of perdition. … Do you not remember that when I was still with you I told you this? And you know what is restraining him now so that he may be revealed in his time. For the mystery of lawlessness is already at work; only he who now restrains it will do so until he is out of the way. And then the lawless one will be revealed, and the Lord Jesus will slay him with the breath of his mouth and destroy him by his appearing and his coming” (2 Thessalonians 2:1-3, 5-8).

A member of The Church of Jesus Christ of Latter-day Saints reading of the passage would suggest that Paul recognized that the apostasy was already underway. Moreover, he knew that the force restraining it — inspired prophetic and apostolic leadership — would not remain on earth forever. Once the apostles were gone, apostasy would continue unrestrained until the Savior’s second coming. Properly understood, Paul’s comment affirms both a looming apostasy and the vital importance of apostolic authority.

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