An unusual and confusing way to define atheists.
By saying "refusing the belief" you seem to be implying it is positive choosing action. I don't see it that way and I think many atheists are similar. I don't choose to refuse belief in God - I am compelled to disbelief.
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The definition I give is the usual in philosophy and common language from the Modern Age. It was used by Rousseau, Voltaire, Diderot, d'Holbach, Marx, Russell, Th. Huxley and almost everybody. It is clear and distinct. The atheist affirms that God doesn't exist. The agnostic neither affirms not denies, he refrains from. It is based on the truth or falsity of a proposition that seems to be more clear that "belief" that is an indeterminate psychological state.
What you means with "atheist" is almost unknow in Europe and in academic circles. See, for example, the definition in the reference French dictionary, Trésor:
Qui nie l'existence de Dieu [Tout court]).
(He who denies the existence of God)
Here the ethimology:
atheist (n.)
1570s, "godless person, one who denies the existence of a supreme, intelligent being to whom moral obligation is due," from French athéiste (16c.), from Greek atheos "without god, denying the gods; abandoned of the gods; godless, ungodly," from a- "without" (see a- (3)) + theos "a god" (from PIE root *dhes-, forming words for religious concepts).
Anyway, I am not intending to launch a words war. Now you know how I use the word and I know how you use the word. Let us pass to more positive things.
There is not a "negative" act. Every act is in function of some causes and motives. Even the abstention is "pasive" only in the sense that means a lack of compromise with two or more parties. But abstention can be responsible or not, guilty or not... In any circumstances, when a judge request it, yo have to justify your abstention. Your "passivity" would be a bad response before a court. It is similar in front to moral or scientific problems. The most common question would be: "Why you don't decide?" Now the ball is on your court.