A few years ago a depressed wife sat in her flat with her sister and daughter. It was December 25th and ever since her teenage years she had lit a candle for Jesus. She was not a Christian, but she liked to light a candle. There was something about Christmas she loved. This year, as she saw Christians celebrating on the TV she suddenly began to call out to Jesus for help with a private problem. A week later she had a call. The problem lifted. And she knew it was because of her prayer on Christmas day. Later she became a follower of Jesus.
Many Iranians are like this lady: they have an instinctive affection for Jesus Christ, and so naturally like the Christmas season when his birth is celebrated. Those wanting to spread the Good News in Iran know this, and so will focus on the Christmas story in their outreach at this time.