Freewill is the God given ability to do anything we want to, either bad or good. God did not want robots who would automatically do His will but people who would willingly love Him and prase and worship Him. Because of freewill, we are all sinners because we all chose to sin at some times, if only in our minds or hearts.
The slang expression, "holy shit!" truly has nothing to do with God at all! It is mearly a dirty expression of exclamation or surprise. A slightly milder version in American slang is "Holy Cow!"