Foreign-language bibles were one of the tools used by the inimitable sci-fi writer R.A. Lafferty (http://ralafferty.org) to gain a reading knowledge of ten languages.
There are two potential problems, as I understand it. First, learning a language, particularly an ancient language, involves learning ancient words for things that have no analog in modern life, whereas translation involves mapping those very things onto their closest equivalent in a modern language. It would be too easy using the interlinear method to start thinking that the Greek word 'krater' means a bowl or cup, when really it is a specific type of bowl used for mixing wine. That can really only be learned by consulting a dictionary, and probably a few pictures.
The second issue is only really a problem for people who are particularly familiar with the text in translation - it's very very easy to start mentally reciting the translation you're familiar with instead of actually parsing the original text. This is one reason that Attic Greek is preferred to Koine (New Testament), even though Koine is generally simpler. Even a secular person usually has enough familiarity with the Bible to make this an issue.
I certainly wouldn't say that this method can't be used profitably, but rather that one should be careful not to fall into those particular traps. The same criticisms could be made to relying on the Loeb editions.
Also, minor nitpick: The New Testament isn't really written in Classical Greek, it's in Koine. Going from Koine to any classical dialect is going to be much more difficult than going from any classical dialect to Koine, due to the simplified grammar and vocabulary of Koine Greek.
Also, while it's true that you're better off learning Attic first, learning some Koine can give some the vocab. and conceptual grounding in the inflections to get a handle on Attic, so long as you don't stick with Koine for years it's not such a bad approach.
I'd like to reiterate that using interlinear translations or Loeb editions wasn't a contraindicated practice, per se. There are just certain problems inherent in the practice that we were advised to look out for. It is certainly a useful tool sometimes.
I think what it all comes down to is what I mentioned above: reading a text and translating a text are fundamentally different. Both require you to interpret a text, but translating a text - particularly an ancient text - require you to interpret it in more and in different ways. So if you're relying heavily on a translation to understand a text you're using tools that mediate between you and the original more than, say, a reference grammar and a lexicon.
I mean, if you're learning English, would you want to start with this?
> Then Joseph being raised from sleep did as the angel of the Lord had bidden him, and took unto him his wife: And knew her not till she had brought forth her firstborn son: and he called his name JESUS.
> When Joseph woke from sleep, he did as the angel of the Lord commanded him: he took his wife, but knew her not until she had given birth to a son. And he called his name Jesus.
https://www.biblegateway.com/passage/?search=Matthew+1%3A24-...
Let's look at your "modern" example. Now, I'm not a native English speaker, but I strongly doubt any English speaker of today would use "He took his wife." to mean "He accepted her as his wife." It would most likely be interpreted as "He brought along his wife." or "Person A kidnapped person B's wife." And "knew her not"? Very few people speak like that, and even fewer would mean "did not have sex with her".
These little details add up much faster than a native speaker may realize.
Perhaps more important is the amount of detail that will never show up in the Bible. Read the entire Bible, and I'm sure you'll never learn what "Never mind, I'm OK.", "Nice to see you again.", or "This section is under construction." means. So, you only learn a small fraction of modern language usage, and you learn it in a mostly anachronistic fashion.
That's true, but I don't think anyone was suggesting this as a technique for learning location-specific idioms or other conversational usage.
One can certainly find more entertaining and less corrected texts :)
> Only if you learn ancient dead languages
You may be surprised by how much of modern communication is influenced by Latin and Hebrew. Mainstream lack of awareness of "old" languages only makes the mainstream more susceptible to influence, as that which cannot be named cannot be firewalled.
You have to be someone who loves these scriptures to be motivated into using them this way.
Many people want to learn a living language: take part in conversation and learn how to say everyday things, and not how to summon locusts upon the land.
Also, judging by the archaic English that is used in English translations of the Bible, I would not recommend them to new speakers of English. You need a thoroughly modernized text which replaces usage like "thy" with "your" and so on.
There is likely a similar issue going to other languages using these texts.
What are some old but non-religious texts which have received careful translations into many languages? Plutarchs Lives, Aesops Fables, folk tales ...?