Helping a non-Muslim son financially hoping that he would accept Islam
16-2-2011 | IslamWeb
Question:
I have a none Muslim son, can I give him money and help him even-though he maybe using the money to buy alcohol and haram things. But through the money and help I can get closer to him and calling him to Alalh, and he may became a Muslim ?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
It is permissible to keep ties with a non-Muslim relative using what is permissible of this worldly matters especially if it is hoped to soften his heart. Allaah Says (what means): {Allaah does not forbid you from those who do not fight you because of religion and do not expel you from your homes - from being righteous toward them and acting justly toward them. Indeed, Allaah loves those who act justly.}[Quran 60:8] Allaah also Says about non-Muslim parents (what means): {…but accompany them in [this] world with appropriate kindness.}[Quran 31:15]
Moreover, Al-Bukhari 
entitled a chapter (in his Saheeh) as: ‘The chapter on keeping ties with a polytheist parent’ and he reported that Asmaa’ 
said: “My mother has come to me hoping to receive a reward from me during the lifetime of the Prophet so I asked the Prophet saying: “May I maintain ties with her (i.e. by giving her what she wants)?” The Prophet replied: “Yes (i.e. be kind to your mother).” Ibn ‘Uyaynah said: “Then, Allaah revealed: {Allaah does not forbid you from those who do not fight you because of religion.}[60:8]”
Also, Al-Bukhari entitled a chapter as: ‘The chapter on keeping ties with a polytheist brother’, and he quoted Ibn ‘Umar 
as saying: “‘Umar saw a Siyara’a (a striped silken) cloak over a man and it was being sold. Then, he requested the Prophet to buy it in order to wear it on Fridays and when meeting foreign delegates. The Prophet () said: “This is worn by the one who will have no share in the Hereafter.” Later on a few similar cloaks were brought to the Prophet (as a gift) and he sent one of them to 'Umar. 'Umar said to the Prophet “How can I wear it, while you said about it what you said?” Then, the Prophet said, “I have not given it to you to wear it, but to sell it or to give it to someone else (to wear).” So, 'Umar sent it to his brother in Makkah before he (‘Umar’s brother) embraced Islam.” [Al-Bukhari]
Hence, it is not forbidden to help a non-Muslim unless one is sure that he (the non-Muslim) will use that in disobeying Allaah, but if one only doubts about this, then it is not Islamically forbidden to help him.
Finally, we advise you to take care of your son and be keen on guiding him to Islam, and you should supplicate to Allaah on his behalf.
For more benefit on calling non-Muslims to Islam, please refer to Fataawa 84345, 88906 and 102075.
Allaah Knows best.