Praise be to Allaah.
Undoubtedly making friends with a kaafir woman will adversely affect her religious commitment, because a kaafir woman does not behave in the same manner or have the same attitude as a Muslim woman, and she does not worship Allaah according to the religion of Islam. Therefore she will not avoid doing things that may adversely affect this Muslim woman who may be deceived by the modest dress or good manners of this kaafir woman, especially in matters that will adversely affect her religious commitment.
Similarly, making friends with her may lead to some kind of approval in one's heart for the rituals that she does as part of her own religion, and this will weaken the sense of friendship and enmity for the sake of Allaah (al-wala’ wa’l-bara’).
Indeed, it may lead some ignorant people to disapprove of the ruling of Allaah that the kaafirs are disbelievers who will abide in Hell forever we seek refuge with Allaah. Hence the Prophet (peace and blessings of Allaah be upon him) said: “Do not keep company with anyone but a believer and do not let anyone eat your food but one who is pious.” (Narrated by al-Tirmidhi, 2395; Abu Dawood, 4832; classed as saheeh by Ibn Hibbaan, 2/314; classed as hasan by Shaykh al-Albaani in Saheeh al-Jaami’, 7341).
We do not mean, however, that this Muslim woman should cut herself off completely from the kaafir woman; she may visit with her, visit her when she is sick and give her gifts, but without forming an emotional attachment or joining in their festivals and celebrations. And the Muslim woman should aim, in those visits and gift-giving, to call this kaafir woman to Islam. This is what our Prophet (peace and blessings of Allaah be upon him) did, as is mentioned in two hadeeths:
But visiting kaafirs in order to have a good time with them is not permitted, because it is obligatory to hate them and shun them. It is permissible to accept their gifts because the Prophet (peace and blessings of Allaah be upon him) accepted gifts from some of the kaafirs, such as the gift from al-Muqawqis the ruler of Egypt. But it is not permissible to congratulate them on the occasion of their festivals because this implies befriending them and approving of their falsehood.
And Allaah knows best.