One reason for postponing deliverance is to give your faith an opportunity to grow stronger. When a mother is teaching her child to walk, she stands back a short distance and holds out her hands to the child, beckoning him to come. Now if she exercises her strength to go to her little one, the child is ill served, for his unsteady legs are denied the practice they need. If she loves him, she will let him suffer a little at present to ensure is future health. Just so because God loves His children, He sometimes lets them struggle to strengthen the legs of their unsteady faith.
From the book "The Christian In Complete Armour"