Steven Guess over at Digitally Arranged raises the issue.
I do think the confusion arises mostly because there is unfortunately a false opposition created in the use of terms like "spirit of the law" and "letter of the law".
These terms imply that there is something “wrong” or “unspiritual” about the “letter” of the law. There is indeed something wrong but the fault is to be found elsewhere, as we shall see.
For one thing, it's the nature of the beast that all "laws" or "instructions" must be applied within a hierarchy of good ends. It has to be so. Otherwise, we would need to have a written law to address every single eventuality in which case there just would not be enough books in the world to contain such a law.
There is, therefore, a natural need for discernment and prayer for guidance and for wisdom for true compliance to “law”, more especially to “God’s law” which is what is in view in Steven’s post.
Of course, there is also the related question, which is hardly ever raised, of whether people have the innate moral ability to keep the “law” or “letter of the law”, if you will.
It is usually just assumed or ignored and hardly ever questioned. Perhaps this is where the difficulty lies. Perhaps the (false) dichotomy created between the so-called “spirit” and “letter” of the law merely masks own moral imperfection.
And, this is exactly the teaching of Christianity and the Bible and the reason why Jesus Christ died for us on the cross.