Siebe,
In the Brahmajala Sutta, the Buddha was referring to brahmins with wrong views on whether the WORLD is finite or infinite (which is different from Ākāsa dhatu).
Akasa dhatu and vinnana dhatu are both infinite and one needs a good knowledge of Abhidhamma or the ability to experience it to verify for himself/herself.
In any case, I think this discussion is not very fruitful. One can believe whatever one wants to and it would not make much of a difference for progressing on the Path. If and when one can get to arupavacara jhana, one will be able to experience Ākāsānancāyatana and Viññāṇañcāyatana.
Please do not post any more on this issue of whether akasa dhatu or vinnana dhatu is infinte or not. That would be a philosophical and speculative discussion.
If Christian would like to, he can share his experience.