What should one do who is afflicted with misgivings regarding ablution and creed, and sometimes feels disbelief for going along with them, being a young man living in Europe who fears for his religion after having been committed?

You must struggle against obsessive thoughts and not give in to them. Know that they do not harm you and do not take you out of the fold of Islam, and your dislike for them is proof of the sincerity of your faith.

As for the causes of recovery from a relapse, they can be summarized as: adhering to supplication (du'a), striving against oneself by performing the obligatory acts and increasing voluntary acts of worship, contemplating death and what comes after it, choosing righteous companions, adhering to gatherings of remembrance (dhikr) and circles of knowledge, and frequently reading and listening to what is beneficial.