This is my opinion.
It is certainly not OK for a believer to ever lie under any circumstances.
I do not esteem those who do, and if on a jury would discount the testimony of an officer of the law who did not uphold God's Decalogue that is implanted in every person's heart.
However, knowing a number of the law enforcement folks of the past, as well as other "investigative" officers, there is never really any occasion for them to lie. The only one who might, is one who is "under cover" and I doubt seriously that any of that sort can be a believer and accomplish much. Again, that is my opinion.
I find those who gather those who lied from the Scriptures and support some scheme of escape for sinful practice a problem.
For that is the ultimate question. Were the examples of those that went about "practicing" the sinfulness without rebuke. The answer is no.
So, as John points out, it is one who continually practices and engages in sinful behavior that is rebuked by God.
John says, "If we say we have not sinned, we deceive ourselves." and further, "If we claim we have not sinned, we are calling God a liar and showing that his word has no place in our hearts."
So, although "all have sinned" - even believers - we have (according to Romans) "no condemnation." Not because we do not sin, but because we are "in Christ" and are called for "His purpose."
