Why do Christians want to dismiss evolution as preposterous on one hand ...?

...and on the other they want to say that God created everyone by using evolution? Can't they make up their minds? Can't they look to Genesis for what to believe on this or did their perfect God somehow screw that up? Is saying the world was created in 7 days really the same as saying it was created in 7 billion years ( or whatever- I'm a free thinker but I'm not a geologist ) ?Is it 'metaphorical' to say that 7 dollars equals 7 billion ( times 365) dollars or is it just a lie? I think you have to ( if you're remotely honest ) either accept the bible or accept evolution but to accept both is an act of pure desperation . I think of these 'christians' as 'atheists in denial'.