It's worth spending at least a few days talking to Christians. Preferably the properly crazy ones - the "God killed the firstborn son of every nasty family in the town and we rejoice at his mercy" crowd. It's fascinating.
That's good, so I hope they would have explained the background to the Old Testament history, the captivity of Children of Israel and typology in order to understand the plagues of Egypt and their significance?
Of course these 'crazy' Christians believe in an unmerciful God that just kills for the sheer fun of it; there was no link with the Egyptians holding Children of Israel as slaves for hundreds of years beforehand, the torturing of them and their children and not to mention the hard labour. From Exodus 3 you couldn’t failed to noted that Pharaoh had the opportunity to let the Children of Israel go to avoid the wrath of God (i.e. rods turning into snakes) and after each subsequent plague Pharaoh had the opportunity to avoid the next. It would be plain to see that each plague wasn't God being unmerciful but this was a direct attack on the god's of Egypt, proving He is the one true God:
Plague 1 - Water into Blood - Egyptian god attacked: Hapi
Plague 2 - Frogs - Egyptian god attacked: Heka
Plague 3 - Lice - Egyptian god attacked: Geb
Plague 4 - Flies - Egyptian god attacked: Khepri
Plague 5 - Death of Livestock - Egyptian god attacked: Apis (sacred bull)
Plague 5a - Death of Livestock - Egyptian god attacked: Hathor (goddess of protection)
Plague 6 - Boils - Egyptian god attacked: Isis (goddess of medicine)
Plague 7 - Hail - Egyptian god attacked: Nut (Sky goddess)
Plague 8 - Locusts - Egyptian god attacked: Seth (god of crops)
Plague 9 - Dark - Egyptian god attacked: Ra (sun god - chief god)
Plague 10 - First Born Killed - Egyptian god attacked: Pharaoh
For example, the first God, ‘Hapi’, the ‘god of the Nile’ – by the water turning into blood this proved ‘Hapi’ was powerless as he was the god that caused the Nile to flood each year, depositing mineral-rich silt.