Belief in Jesus requires that an individual acknowledge Jesus as the son of G-d. In no way did blood on the doorpost imply what each individual in the dwelling believed. In no way does selecting a lamb four days prior to its slaughter imply or suggest in any way that the nation Israel perceived as forgiveness of their sins. And to make such a suggestion is absurd and ludicrous. Nowhere, in the deliverance of the nation Israel from Egypt is there any reference or implication that the blood from the slain lambs required any type of profession of each individual or group dwelling in the structure where the lamb's blood appeared on the doorpost.
Human sacrifice is forbidden.
Murder of a human being is forbidden. The blood from over 400,000 lambs was placed on the doorposts of each house throughout Goshen. The deaths of these lambs were a terrifying sight to the Egytians since they were Egyptian gods. So, in fact, the nation Israel killed the idolatrous diety of the Egyptians and feasted on their bounty before departing. Each Jew proclaimed their allegiance to Hashem by killing the Egyptian god and placing that god's blood on the doorpost.