In De differentiis verborum, under the entry of Clemens, Pompa contrasts that word with placidus, and right afterwards writes:
Sed implacidus, qui nullo placamine ad placabilitatem promovetur, ut se placatum ostendat, videat, annon implacabilem Deum quoque sit experturus.
What I understood thus far:
But the implacidus, without any means of appeasing him (to be pushed by them towards calmness), in order that he might display himself placid. Let him see [?].
I have my doubts also of my interpretation of the first part, but it is in the last section I have greater difficulty with. It seem that I can't reconcile the "(quoque) sit experturus" with the sentence. I was thinking maybe:
Let him see, and find out, doesn't it so, God [also] not able to be pleased.
But in this interpretation, I can't make sense of the word order. And if "sit experturus" related to Deum, shouldn't it be in indirect speech taking the accusative as "implacabilem Deum"?
As as side note, I would like to ask if we can connect the "ut se ..." with "videat ..." [ in order to x, do y], but as far as I saw, ut in that sense always comes after the clause?
Edit: Thanks for the helpful answers.Reading them, I would like to suggest my own which is kind of merge between the two and has softer and less harsh tone, which I prefer:
But the implacidus, who by no [regular] means of appeasing is moved to placability, Let him consider, in order that he shows himself placid, whether he will not find God to be implacable as well.