You are reading into it and making up something that has no parallel. The blood was a sign.
Apparently, the all knowing God in this instance could not tell which household was Egyptian and which Hebrew, so He "needed" a visible marker!
For I will go through the land of Egypt on that night, and will strike down all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgments—I am the LORD. [Ex 12:12]
"The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land of Egypt. " [Ex 12:13]
Also, previous verses show that the lamb could be a goat! [Ex 12:5] The lamb did not atone for their sins; and no one was drinking its blood.
The lamb WAS sacrificed for the life of the inhabitants of that house
This "sacrifice" was not to atone for any sins.
Apparently, the all knowing God in this instance could not tell which household was Egyptian and which Hebrew, so He "needed" a visible marker!
It could also be seen as those who follow the L-rd's commandments are saved; Jew or gentile. Those who refuse to do what the L-rd commands; Jew or gentile will perish. Being a member of a denomiation will not save; calling on the Name of the L-rd will save. That is one way to spin it.
shalom b'shem Yah'shua
Kosta, I’d look at it this way.
God didn’t need a sign. I think that it was for the Jews themselves to discover if they had the courage to display that sign on their doors. I think that it was a test that was set up, as we would set up a test for children in order for them to prove to themselves how brave and steadfast they were.
I think that our own signs that we display are also telling. Our HR director has a Rosary that he drapes over his daytimer planner; it’s inconspicuous, yet there. I wear a beautiful gold Celtic cross that occasionally peeks out over my shirt. I drape a Rosary over my rear view mirror and have finger rosaries on my car key rings.
I am proud and brave enough to display my Christianity to the world. I am not ashamed to pray before meals. These signs that we display are our proofs to ourselves, not necessarily to God.