According to howtorepent.org good Christians have some work to do. It seems the Bible lists 667 sins. From birth God records every transgression in his Book of Sins. Failure to repent even one of those 667 sins guarantees a one way ticket to Hell. God’s sin list is staggering, as is the preamble and content contained in the link below.
Click to access 667-Sins-List.pdf
Ponder 667 sins, then name a single Christian who rises above the sin test. Why is it that theists claim moral superiority yet spend a lifetime repenting sin?
notestoponder 
I remember reading somewhere that the words “sin” and “repent” are bad translations from the Greek in which the bible was first translated. Today “sin” would be translated as “bad choices” and “repent” as “transform”.
This doesn’t explain why almost 2000 years of christian ‘leaders’ have been threatening hell and doom to those that make bad choices (i.e. life’s experience) and do not repent (i.e. learn and do better).
Bad translation and sick leadership sums it all up.
A “list of sins” would be considered as living under the law, as in “thou shalt not” or “thou shalt” (do this or that) but according to Christianity Jesus’ death on the cross was propitiatory for all who believe in it, therefore sins are no longer listed. Christians were quick to latch on to the shortcut to sanctification by works provided by Paul of Tarsus: grace. “For you are saved by grace through faith, not by works so that no one can boast” therefore they can claim to be instantly and forever “saved” simply by believing in Jesus and claiming that, regardless of their sinful status. “The blood cleanses us from all sins” and all the rest. Christians do not repent and do not change from their evil ways because by some ass-backward theology they can claim that repenting actually translates as admitting to a lack of faith in the power of the blood of Christ. That is the kind of twisted reasoning non-believers are often not aware of when they encounter that dangerous alien species known as Christians. Although they are “warned” against such, “Shall we sin more that grace may abound the more? God forbid!” or something to that effect, they love their Bible selectively. A Christian’s claim to moral superiority does not come from “being” but from “believing”. Another word for that is exceptionalism.
While in the subject, let me explain what “sin” is. Sin is anything that in thought, word or deed causes distress, harm, pain, loss to anyone for my own satisfaction, benefit, entertainment. The only counter to “sin” I have found is not faith in some questionable deity, but in living a compassionate life from the basis of empathy.