Were that true, we would have seen all the people from the area not eating shrimp, or we would have seen the people who did eat the shrimp having higher rates of mortality. Actually the Ancient Egyptians, Persians, Romans, Greeks etc. managed to do quite well while still eating seafood. And indeed Christianity only spread when it was adopted by the Romans and Judaism was never as powerful as those civilisations.
The bible makes a number of quotes about free will, and how God gave us free will so that we are free to choose him or not. Right from the book of genesis, free will is a strong theme in both testaments. Seems strange that God gave us the choice to sin or not, but many Christians would prefer to take away that free will and force us to follow God's will regardless of how we feel about God, or even if he exists or not.