I have just noticed, why is temptation rendered "costning", rather than something like "forseeking" or "forleading"?

"Costen" is a now-defunct word meaning 'try, tempt', from O.E. "costian, costnian." I prefer it because it keeps the old understanding of temptation as a test or trial for the faithful (that's was Latin "tentatio" means as well).

Ahh I recognise it now! It is somewhat related to Dutch "kiezen", and I have it in my own language project as well in the form of "keusan"