That reasoning ticks me off more than irrational fear does. I'm a Christian and own 10 snakes, and I hear this sort of thing all the time! "Satan was a snake, so that means snakes are evil!"
I usually then provide an argument for that by starting that there are stories in the Bible that had snakes portrayed as good guys as well; in Exodus when Moses turned his staff into a snake to show off God's power to Pharaoh. And before that when God was talking to Moses through the burning bush and Moses was afraid of the snake, God specifically said not to be afraid of snakes!
Then when they try and go on, I interrupt by stating that Jesus once compared HIMSELF to a snake and that Christians are suppose to be "wise like serpents"! And in Proverbs, it specifically says that God loves snakes, and since God hates evil then that means snakes are good (with the obvious exception to Satan). After that they either shut up or get mad at me for exposing that the real reason they don't like snakes is because of simple irrational fear hidden by religion.
*Sigh* Sorry to get the topic off track, but that's just my biggest pet peeve: people using religion as an excuse to hate snakes, especially when the Bible says otherwise.