The Mekhilta pinpoints the exact moment when Israel first declared (Exodus 15:11): "Who is like You among the mighty, O Lord?" It was not during the plagues. It was not at the moment of departure from Egypt. It came only after Israel saw three things happen simultaneously at the Red Sea.
First, they saw that Pharaoh and his hosts were lost — swallowed by the waters, gone without a trace. The most powerful army in the known world vanished in an instant. Second, they saw that the rule of Egypt had been abolished. Not merely weakened or humbled, but permanently broken as a force that could dominate Israel. Third, they saw that idolatry had been castigated — the gods of Egypt, in whose name Pharaoh claimed authority, were exposed as powerless frauds.
Only when all three conditions were met — the army destroyed, the empire broken, the false gods humiliated — did Israel open their mouths and sing. The song was not premature celebration. It was a verdict rendered after the evidence was complete.
This reading from the Mekhilta DeRabbi Yishmael (Tractate Shirah 8:1) suggests that genuine faith requires visible proof. Israel did not sing because they were told to believe. They sang because they saw. The Red Sea was not a test of blind faith — it was a demonstration so overwhelming that the only possible response was "Who is like You among the mighty?"