Is a Muslim's lack of hatred for a Christian considered a sin?

Among the requirements of faith are love for the believers and hatred for the disbelievers. Hatred for the disbelievers is an obligation, and whoever abandons it commits a sin, as stated by Sheikh al-Islam Ibn Taymiyyah. However, hating them does not mean oppressing them. Rather, Islamic law permits showing kindness to those among them who are not at war with Muslims, especially relatives, in order to win over their hearts.