I'm sorry, but your example sentence made me wonder: when the verb is the last word in a sentence, shouldn't it be in its infinitive form? So, it would be "[...] dat ik tegen corruptie zijn", wouldn't it? Please correct me if I'm wrong :). And thanks for your explanation about the tegen! =)
Sentences typically have a conjugated verb. They may or may not also have an infinitive as a complement to the conjugated verb. Examples:
I go downstairs
I go to sleep
The first sentence above has no complement. The second has an adverb as a complement. The third has an infinitive as a complement.
The subject of a sentence usually is followed by a conjugated verb, which must agree with the subject (for example, "I go" but "He goes").
An infinitive can also be used on its own as a subject. For example, "To love is a wonderful thing".
In the Dutch sentence here, "mij" is not an indirect object. Rather, it is an object of the preposition "tegen".
A true indirect object is used without any preposition at all. It is only word order (or in some languages, case) that identifies it as an indirect rather than a direct object. For example:
He gives me a pencil.
Hij geeft me een potlood.
In the above, "me" is an indirect object.
I do not recall "tegen" being mentioned as also meaning "to"
DL does not usually "mention" things at all (except sometimes in the Tips and Notes (which PC users can see, but smartphone users cannot).
Instead, DL just brings on the sentences, and by considering them, you figure out what is going on.
Some people like the DL approach because it spares us wordy descriptions of grammar. Others don't like the DL approach; they feel it is unfair and causes them to lose hearts or whatever.
Personally, I like using DL for practice, but I go elsewhere (including the discussion pages) for explanations of grammar and usage.