Quick thought on Parshat Bo:"Coming out" as Jews

Exodus, chapter 12, verse 13:

יג וְהָיָה הַדָּם לָכֶם לְאֹת, עַל הַבָּתִּים אֲשֶׁר אַתֶּם שָׁם, וְרָאִיתִי אֶת-הַדָּם, וּפָסַחְתִּי עֲלֵכֶם; וְלֹא-יִהְיֶה בָכֶם נֶגֶף לְמַשְׁחִית, בְּהַכֹּתִי בְּאֶרֶץ מִצְרָיִם.	13 And the blood shall be to you for a token upon the houses where ye are; and when I see the blood, I will pass over you, and there shall no plague be upon you to destroy you, when I smite the land of Egypt.

Nowhere in the above text does it say that HaShem/G-d needed to see the blood on the doorposts to know where the B'nai Yisrael/Children of Israel were located. In my opinion, what was important to HaShem was knowing who among our ancestors were willing to identify themselves publicly as Hebrews.