So to be a Christian you have to become a miserable person who’s allowed to enjoy nothing?
Its not about ALL Christians can't do those things, but SOME certainly shouldn't.
For example, a car in itself is NOT sinful for everyone. It is nothing more than a mode of transportation. For others, they baby their car, name it and place its value above their value of God.
In such a case, they have made an idol of the car... in which case it is NOT the car that became sinful, but the place in the individual's heart that made it sin.
IF someone values their TV more than they value God... then yes... the TV to them has become an idol... so while perfectly acceptable for some, not so much others.
We are no longer bound by the black and white of law, but are to be led by the Spirit, following the one that gave the law. IF that Spirit inside says "do not do _________" and you do _________ you have disobeyed.
It is that disobedience that is the big deal... not that Christians can not have fun... it is that what is good for one, may not be good for another as we are all different.
Just like one person can have an alcoholic beverage, but a recovering alcoholic is best to avoid even one. We all place different values on different things. THAT is why discernment with the Holy Spirit is so vital in the walk with Christ... the Spirit knows what is of benefit and what is a detriment to the one the Spirit is speaking to.
Look at Jesus in the wilderness, He could have turned the stone to bread... He had the ability, yet He didnt. Is it sin to eat after having not had anything to eat for 40 days? There is nothing wrong with eating itself... but Jesus was not told by the Father to do so..... so He didnt.
IF He had given in to temptation and turned it to bread and ate... not a big deal in the eyes of men... He would have leaned on mans logic rather than obedience to the Father... THAT is where the issue is, not in the act itself, but obedience.
Its not an issue of "no fun" but rather... what is best for the individual. It doesnt mean "law for all Christians" because it is not good for some.