The Lord is dealing with him/her in a strong way. There is no other reason why this person would act in such a manner if His grip wasn’t fastening upon them.
We should pray for this person (as we would for any lost person), and let the Lord finish His work.
Those who mock God will, at some point, find themselves weeping at His feet. I know because I was one of them.
**“O my Jesus, forgive us our sins, save us from the fires of hell, and lead all souls to Heaven, especially those in most need of Thy mercy.”