My question might seemed like I am atheist but no I am a believer in God. But this is a question kids nowadays use to ask. Here is what a kid told me: "If God does good things for us, fine that our parents or friends also do, but we don't worship them, we just say 'Thank you' or show gratitude but we donot pray them again and again, then why should we pray God and what will God find good if we are just chanting his name again and again" I find it tough to answer. So seek some help on making him understand why should we pray/worship/chant.
This is a good question and a difficult one too for making it understand to kids. Good that you have pointed it out. So, let me try to explain. I won't say that its written in books that Gods say worship me and that's the way you will attain Moksha. That might be correct but might not be a good answer for a kid. He/she might not understand what is Moksha and that will lead to another big confusion. Initially, kids are ignorant towards God and to make them inclined or to create their interest is to show them stories of Gods like Ramayana, or other adventure or moral stories. This will actually not burden them as now they are not doing it forcefully, they are just watching something which is close to what they like or what they watch usually. You can choose the format you like, ie, story telling, story books, small animation films or TV series, etc. Now, when they start taking interest or they started treating Gods like their hero, you can arrange a quiz between some of his friends and him and ask questions related to Gods and religion. This way he will remind himself of whatever he had seen/read/heard till now and will answer (in a way you are testing how much does he admire God now) and if other kids answer correctly then also he will learn from them (kids pay more attention to what other kids say rather than elders). Also, ask them what are the good qualities you find in a particular God, eg, Lord Rama. So, that way they will become interested and will try to find good qualities in their God. Then slowly slowly as the interest grows tell him about that we do lot of sins everyday and we should ask for forgiveness from Gods. Make some suitable time for him such that in morning, we should ask God to help us in dealing with the troubles all through the day (a form of praying), similarly at night before sleeping make him realize what troubles he could faced during the day but due to God's grace he was comfortable all through, make him thank God for that, if he has done something wrong during the day, ask him to seek forgiveness to God and to try not repeat the same mistake. At the eating time also, you can ask him to thank his mother for preparing food and when he is thanking mother, then let the mother say that this is by God's grace that we are able to have this food today else it was difficult (tell some problem), so we should thank God that we able to have this. This even if might be a false statement initially but this will tell the child in his way that he is not praying but actually thanking God. Slowly, he will learn thanking God or seeking his help. This all we are doing because we are going according to the child's mindset. We know of lot of things why we should pray God, God has created everything, he is our saviour, etc but these are a bit difficult for a child to understand by direct preaching. Hope this helps.
I believe you will get many answers and opinions in this matter. Here is one such opinion :)
Kids are the new generation. Their minds are pliable and they listen to what parents and elders tell them (mostly). That does not mean one can put upon the child all the beliefs that One thinks is right. For instance, does the parent know for sure that one must pray to God? Does the parent know who God is? Does the parent know why one must pray? Then how can the parent/elder force upon the child these beliefs which he/she himself/herself is unsure of. This is the age to explore, to seek, to find, to follow. The duty of elders is to create the right platform for the children to explore.
For example, think of a game. One likes one sport but someone else likes another. This is because when it comes to sports, parents give the right platform for their children to explore, to play different sports, to play what they like (without abusing others/themselves). That helps the children to grow into lovable beings. Sportsman spirit is developed. However when it comes to religion, parents always use words such as 'you SHOULD pray' 'God will PUNISH if you don't' etc. (Please note that this is in no way targetted towards the OP or any other specific parent).
There are many many paths to God. One of them (some say it is the best of all paths even!!) is Bhakti or doing prayer. Even in Bhakti there are various ways to do it. Pooja, Japa, Dhyana, Smarana, Vandana, Pada namaskar, Kirtan, Sharvana, Reading, Seva, etc. So the duty of the parent is to say "Prayer is good, there are many ways to pray. You yourself pray and find out for yourself whether or not your quality of life changes, I will provide the right platform to do so." Provide right platform for child to seek and find out what prayer is and how it transforms the child, without abusing others/himself. :) Ensure that good values are being cultivated, like forbearance for others, patience, love for fellow man (and woman), respect for animals, service to humanity, right attitude towards knowledge (knowledge is continuous and evolving, but being knowledgible does not make one superior to others!), finally respect for all religions and ways of life. (in a childish note, God will be happier if His children are good but do not praise Him, rather than if they praise Him and cut the throat of another.)
Secondly lead by example. Seek for yourself, Who GOD is. What prayer is? Why should one pray. When you truly pray and seek God with your Heart, you will yourself be transformed isn't it? On seeing your efforts and seeing the transformation that occurs in YOU as a result of your prayers, the child will be naturally transformed :) All the best sir.