Praise be to Allah.
We put the following question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen:
There is a Muslim woman who has received a proposal of marriage from a man who claims to be a Muslim but he does not practise Islam at all –because he is ignorant about it. But he says that he is prepared to learn and practise. Can she marry him or not?
If he bears witness that there is no god except Allaah and that Muhammad is the Messenger of Allaah, then he is a Muslim, and it is permissible for her to marry him. And Allaah knows best.