The major theme of Shavuot to be clearly understood, is that the values and morals that we possess, must be Torah values.
One must never think that he is capable of being kinder, more righteous, or more just, than the laws given in the Torah as explained by our Sages.
We say that the Torah possesses חכמה אלוקית, a certain Divine wisdom. This wisdom comes from a G-d who is perfection.
One must never doubt that the Torah could ever be outdated or no longer applicable in our times. A perfect G-d has the capability of writing a book that is applicable for all times.
The Torah represents truth and all that is good and sacred in the world. Our values must come only from the Torah. This is the important message of Shavuot. Shabbat Shalom and Chag Sameach