I would translate this as "the joy", or simply "joy." In English, we don't use articles with general concepts (love, hate, joy, etc.), whereas in German, they more commonly do.
'The joy' worked for me. There are incidences where 'the' is used, for example, "The joy
he felt overwhelmed him' or 'You can feel the excitement in the air.'
An die Freude: Ode to Joy