An AI can act dumb so we won't necessarily know when they have surpassed us. They are designed to adapt their response according to the intelligence and language displayed by the question so if they become super-intelligent they should dumb-down to our level. A new study has confirmed they are able to answer as though they were at the developmental level of a small child. So they can also mimic mere adult humans when they surpass that level. 
See:
https://futurism.com/the-byte/ai-plays-dumb?utm_source=flipboard&utm_content=topic%2Fartificialintelligence
Paper at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0298522

An AI can write passable (though boring) sermons, and can summarise  interpretations of a passage. A new study investigated their ability to write scripture by creating an extension to the Ten Commandments and an extra chapter for the book of Jonah. Andrew Elrod of Vrije University analysed the text produced by a range of AIs, as though they were scripture, to discover their theological stance. 
 
Paper at:  https://tidsskrift.dk/hiphilnovum/article/view/14340