BEIRUT — A week after Islamist rebels swept suddenly into Aleppo, members of the city’s dwindling Christian community are wondering again what future is left for them in Syria.

       Over nearly 14 years of civil war, Aleppo’s Christian population has fallen from 300,000 to just 25,000, as many have left the country for better opportunities and a life free from the threat of violence. In 2013, two of the city’s archbishops were kidnapped; their whereabouts remain unknown.