Do not kill your conscience. Be committed to excellence. It is a great danger to justify any sin, no matter how small, that is what 'commitment to excellence (perfection)' is all about.

Evil thrives, not with sins, but with its justification. Our business is with humility and trust , not with the justification of sins. There is an element of pride lurked at the background of either justifying a sin or worrying stiff about its occurence. Either way, there is the root of falsehood at play: Pride! This is the tool of the devil,even in the guise of goodness. We are all sinners, no more. 

Evil is also very much at play when we worry, and the good guys are guilty of this. At the end of the day, there is only one sin: falsehood. In Christ who is Truth , sin does not exist, Even sin can be conquered byTruth.