Says who? Can you cite chapter and verse for these claims?
Galatians 5:19-21 (NASB)
Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality, idolatry, sorcery (see note below), enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions, envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God.
Note: The word translated "sorcery" is the NT Greek word φαρμακεία (pharmakeia) which has multiple meanings:
1) the use or the administering of drugs
2) poisoning
3) sorcery, magical arts, often found in connection with idolatry and fostered by it
So, in the NT times, there was a correlation between drug use and sorcery. This is often a text used to explain the Christian prohibition against drug use, especially those used with pagan rituals.
Also, there are general principles that Christian should consider when approaching drug use.