In every post, my site leaves a space after the footer. How do i remove this space? http://www.christiantruthcenter.com

not sure what space you mean - on single post pages or multi post pages?
can you show it with an image and point to the space you mean.

this is the space am taking about. the space i have pointed with arrows in that attachement

That looks like it may have something to do with a plugin you have installed. Try deactivating all your plugins as a test. If the space goes away start activating one by one till you fine the problem plugin.

the problem seems not to be a plugin problem since after deactivating all the plugins, the space remains

Looking at the page source, I believe your issue is caused by a plugin. Please shutoff ALL plugins and I will look at the page again.