De or het christensocialist?

The correct Dutch article is:

de christensocialist

Rule Words ending in -ist: almost always de. See the rule

How to use christensocialist

the christensocialistde christensocialist
this christensocialistdeze christensocialist
that christensocialistdie christensocialist
our christensocialistonze christensocialist
your christensocialistjouw christensocialist
every christensocialistelke christensocialist
which christensocialist?welke christensocialist?
a big christensocialist / the big christensocialisteen grote christensocialist, de grote christensocialist