Every ship is not fit for the same service, every Christian cannot do the same work. In some harbours you may see the "block-ship," an old man-of-war that has become inefficient for active service through age, but it is now useful as a defence of the port. If a man cannot fight in the evangelistic field, he may, if he belongs to the army of God, defend one or other of the forts of Christianity. A consistent life is always a good defence.