“Let the Christian parent explain to the child what prayer is. Tell him that God answer prayer. Direct him to the Savior. Then urge him to express his desires in his own language, both when he rises and when he goes to rest.
You will be amazed, and, I may add, sometimes amused, too. But you will be frequently surprised at the expressions they will use, the confessions they will make, the desires they will utter. I am certain that any Christian person standing within earshot and listening to the simple prayer of a little child earnestly asking God for what he thinks he wants would never afterward wish to teach a child a form. Rather, he would admit that, as a matter of education of the heart, the extemporaneous utterance was infinitely superior to the best form, and that the form should be given up forever.
However, do not let me speak too sweepingly. If you must teach you child to say a form of prayer, at least take care that you do not teach him to say anything that is not true. As far as possible, never put into a child’s mouth a word that the child cannot truly say from his heart.
Insist with all your heart that religion is solemn reality not to be mimicked or pretended. Seek to bring the child to understand that there is no vice more abhorrent before God than hypocrisy. Do not make your young Samuel a young hypocrite, but train up your darling to speak before the Lord with a deep solemnity and a conscientious truthfulness. If you must have a form of prayer, let it not express such desires as a child never had, but let it be adapted to his young capacity.
I beseech you, though I scarcely need to do so, for I know how zealous you are in this matter, as soon as you see the first peep of day in your children, encourage their young desires. Believe in the conversion of children while they are children. Believe that the Lord can call them by His grace, can renew their hearts, can give them a part and a lot among His people long before they reach the prime of life.”
Taken from the book Spiritual Parenting, by C. H. Spurgeon.