To fully appreciate the story of Jesus cursing the fig tree, we should bear several things in mind.
For one thing, the Old Testament prophets often performed symbolic acts to gain attention and convey their message. Jeremiah, for instance, was ordered to break a potter's flask in Israel's sight, as a symbol of how God will smash Israel (Jeremiah 19).
The Hebrew Scriptures often use figs or the fig tree as a symbol of Israel. In Hosea, for example, we find God saying, "Like grapes in the desert, I found Israel. Like the first fruits of the fig tree in its prime, I considered your fathers" (Hosea 9:10).
The point, then, for the apostles is the fruitlessness of the worship and piety at Jesus' time. Like the fig tree's abundance of green leaves, the activities of the Temple give the impression of religious vitality, but the Temple worship is barren.
Jesus' action, then, is prophetic and symbolic. And in the dark days ahead, the apostles are to recall the power of Jesus' word. They are to continue to have faith in Jesus and act out of faith. Faith in Jesus and the power of their prayer will enable them to overcome all obstacles.