He became Muslim then he did something that is nullifies Islam, out of ignorance

Praise be to Allah.

He should be dealt with in the way that is better, and he should be told that this is something that nullifies Islam, but there is no need for him to renew his Islam, because this contrary action that he did is something that he was unaware of, and Allaah says (interpretation of the meaning): 

“And We never punish until We have sent a Messenger (to give warning)”

[al-Isra’ 17:15] 

“And never would We destroy the towns unless the people thereof are Zaalimoon (polytheists, wrongdoers, disbelievers in the Oneness of Allaah, oppressors and tyrants)”

[al-Qasas 28:59]. 

The one who is ignorant is not a wrongdoer, because he did not mean to sin, especially if he is new in Islam. End quote.