There is nothing wrong in giving the zakah to the non-practicing or misguided Muslim in an attempt to win his heart and help him to be religious. This is one of the means to guide the misguided and bring them back on the track of Islam. However, zakah should not be given to anyone who may use it to launch war against Islam and Muslims.
Dr. Muzammil Siddiqi, former president of the Islamic Society of North America, states the following: Primarily, zakah is to help the poor and needy Muslims. It can also be given to ‘those whose hearts are to be reconciled to Islam’. Referring to this, Allah Almighty says: (The alms are only for the poor and the needy, and those who collect them, and those whose hearts are to be reconciled, and to free the captives and the debtors, and for the cause of Allah, and (for) the wayfarers; a duty imposed by Allah. Allah is knower, Wise.) (At-Tawbah 9: 60)
This means that even a non-Muslim can receive some zakah, if there is a hope that he/she can be guided to the truth of Islam. Similarly, if you think that by giving zakah, you can win the heart of a misguided Muslim and bring him back to Islam, then zakah can be given to him.
According to some jurists, such people also come under the category of mu’allafati qulubuhum or those whose hearts are to be reconciled. You can help him with zakah and remind him to follow his religion. Perhaps by this good treatment he will come back to Islam. Very often, we Muslims give da`wah to others, but we do not take care of their physical and financial needs. Poverty sometimes pushes people to neglect their faith. The Prophet (peace and blessings be upon him) is reported to have called poverty “an evil that sometimes makes people forget Allah.” (Reported by At-Tirmidhi)
However, we should also be careful in giving zakah. We should not give zakah to any one who may use it to indulge in sins or to rebel against Allah and Islam.