Anything which becomes an idol in the temple (which is us) that is when it becomes sinful. There are many gray areas of course and we could spend much time looking at gray-area circumstances, but that is why each person has a walk and each person must examine themselves whether they be in the faith.
You made some great points Seth
I know Paul never spoke of "pot smoking " in the Word
but He did become all things to all men that he might save some
and Jews dont eat pork to be a Jew when with them he did not eat pork .. with the gents he ate whatever they offered him , thankful for the opportunity to labour in love to the gentiles
to me it so depends on the circumstances , His faith and more so grace of God was so strong through his walk
He rejoiced through the suffering for all men ...
wow , he said idols are nothing / vanity , to many bellies gods/ men
But if any man love God, the same is known of him. 1Cr 8:4 As concerning therefore the eating of those things that are offered in sacrifice unto idols,
we know that an idol [is] nothing in the world, and that [there is] none other God but one.
Paul said we know by the Spirit of God that, but many DO NOT know that 
1Cr 8:5 For though there be that are called gods, whether in heaven or in earth, (as there be gods many, and lords many,)
1Cr 8:6 But to us [there is but] one God, the Father, of whom [are] all things, and we in him; and one Lord Jesus Christ, by whom [are] all things, and we by him.
1Cr 8:7 Howbeit [there is] not in every man that knowledge: for some
with conscience of the idol unto this hour eat [it] as a thing offered unto an idol; and their conscience being weak is defiled. 1Cr 8:8 But meat commendeth us not to God: for neither, if we eat, are we the better; neither, if we eat not, are we the worse.
1Cr 8:9 But take heed lest by any means this liberty of yours become a stumblingblock to them that are weak. But if any man love God, the same is known of him. but how do you reach a drug addict ? by forcing them to stop ,
knew a man who loved his pot , a good man to who loved God and tried so hard to stop , went to a church and all them voices caused him to stumble and he is for the worse and not the better over the whole ordeal , alone and hurt not able to trust , the church voices made him fail more than his smoking ever did .
I am be no means justifying him or them for what is done in the name of God but
just saying, many times force gets you no where but a little love / and faith mixed with grace and understanding goes a long long ways ,,,,,,,,,, our strengh is in God not in ourselves or anyone else to get us all though this life , sometimes His grace is just sufficent and thats all we got .
