Apparently, the new Reformation Heritage Study Bible includes the comment, ‘Justification is the change of man’s moral nature; every justified man is a changed man.’
Not being madly keen on study bibles in general, I haven’t seen the Reformation Heritage one to find out for myself whether it does indeed say this. I sincerely hope it doesn’t, because however true the second half of the sentence is in the right context (and incidentally it’s also true for women, and children), the first half is simply false.
It would in fact be an egregious blunder for anyone claiming to be reformed to say that justification is the change of our moral nature. Justification has nothing to do with our moral nature, or anything in us at all – it is entirely to do with our legal status, an act passed on us.
If you want to talk about changing our moral nature, that shifts the discussion into the realm of sanctification. Sanctification is something internal, whereas justification is purely external – sanctification changes our heart inside us (from sinful to holy) while justification changes our legal relation to God outside of us (from condemned and alienated to pardoned and accepted).
Although it is true and important that those who are justified are from that point onwards being sanctified, it is essential to be clear that (and how) justification and sanctification are distinct. Larger Catechism 77 should help anyone in the Reformed world who might be in danger of getting confused (or the whole section from 69 to 78). Meanwhile teaching which blurs the distinction in such unequivocally wrong terms as the actual statement that justification is the change of man’s moral nature is not reformed – is compatible neither with Scripture in the first instance nor the standards – but is instead seriously erroneous.