Beside the ton of evidence about evolution (look up Aron Ra on Youtube, he has hundreds of awesome videos on the topic), he's discrediting religions while trying to discredit science.
His argument is like "you have faith in science that isn't proved or provable, and yet you have the nerve to reject god that isn't proved or provable?"
Uhmm, yes. Except, as we now, the first sentence of his assertion is false.

Nope there is so much evidence for evolution its ridiculous but giants really you can't just scale things up and expect them work just look at the life expectancy and health problems for the few people who have grown over 8ft (usually due pituitary glands going haywire) short lives with many health issues the skeleton pics that are bandied about the internet would not be possible

nope not even remotely true. people say all kinds of crap. that's what it is: crap. dietl goes into detail; i can't improve on that. i can add my general disdain for people who present what amounts to conspiracy theories to attack well-proven scientific "theory" (theory doesn't mean the same thing to a scientist as it does to everyone else). feh! there. that was my disdain.

g

There is tons of evidence for evolution. Genes, the fossil record, speciation has even been observed. To deny evolution is to deny reality. There is no faith involved.
Scientist only know that dark matter is there because we can see the effects of dark matter. So there is evidence, again no faith at all.
I would like to see evidence for the claim that evidence of human giants got destroyed. And if there is no evidence left why should we believe without evidence that it is true. But all this is idiocy anyway. It is very clear that the person you are talking to heavily relies on the bible to support his ludicrous notion that giants existed. And the bible is just a text that was written by (by todays standards) uneducated, primitive people who knew next to nothing about the world. To rely on this for empirical knowledge is childish and stupid, as is the believe in an evil boogie man that secretly controls the world. If you ask people who believe in Satan what constitutes as satanism the answer they give often mentions banal stuff like heavy metal, atheism, Miley Cyrus or Ze JEWS! Those people are not worthy of any attention.