De or het wederoproeping?

The correct Dutch article is:

de wederoproeping

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

How to use wederoproeping

the wederoproepingde wederoproeping
this wederoproepingdeze wederoproeping
that wederoproepingdie wederoproeping
our wederoproepingonze wederoproeping
your wederoproepingjouw wederoproeping
every wederoproepingelke wederoproeping
which wederoproeping?welke wederoproeping?
a big wederoproeping / the big wederoproepingeen grote wederoproeping, de grote wederoproeping