"Then the LORD appeared to Solomon by night, and said to him: 'I have heard your prayer, and have chosen this place for Myself as a house of sacrifice.'" 2 Chronicles 7.20
I believe that prayer is effective only when it is sincere. Without sincerity, it’s useless to say many words. It's like sowing in the wind. Also formalities, like being on your knees or attending church, do not guarantee answers. What really counts is a contrite, broken and repentant heart, which characterises sincere humility.
