From the link posted by Paul Vargas, found here:
Our restatement of Sharp’s rule is believed to be true to the nature
of the language, and able to address all classes of exceptions that
Winstanley raised. The “Sharper” rule is as follows:
In native Greek constructions (i.e., not translation Greek), when a
single article modifies two substantives connected by καί (thus,
article-substantive-καί-substantive), when both substantives are (1)
singular (both grammatically and semantically), (2) personal, (3) and
common nouns (not proper names or ordinals), they have the same
This rule, as stated, covers all the so-called exceptions. Further,
even the exceptions do not impact the christologically significant
passages in the NT, for the semantic situation of Titus 2:13 and 2 Pet
1:1 is outside the scope of Winstanley’s counter-illustrations.
Winer’s opinion notwithstanding, solid linguistic reasons and plenty
of phenomenological data were found to support the requirements that
Sharp laid down. When substantives meet the requirements of Sharp’s
canon, apposition is the result, and inviolably so in the NT. The
canon even works outside the twenty-seven books and, hence, ought to
be resurrected as a sound principle which has overwhelming validity in
all of Greek literature. Consequently, in Titus 2:13 and 2 Pet 1:1 we
are compelled to recognize that, on a grammatical level, a heavy
burden of proof rests with the one who wishes to deny that “God and
Savior” refers to one person, Jesus Christ.
In other words, based on the research presented in the above article, Granville Sharp's rule is both valid and applicable in these passages.