Temporary Resident Card for Kid

YEs. The (kid's) paper resident card is a valid travel document.

Thanks..

OH NO NO NO NO.
A residents' card is NEVER a valid travel document.
You must use a travel document to travel. Usual examples are passports, national identity cards, refugee documents, specific laissez-passer.
It is untrue that under 5s cannot get residents' cards in Belgium.
Please ask again for one and carry it with your valid travel document.
Of course the alternative to a residents' document for a child if you are wishing to prove where currently living is a "composition de menage" which you might be lucky enough to get from your maison communale for free if you explain why you need it.

meaning is that, Passport + Paper Resident card is fine...

Yes that is fine, passport + residents' document + parent of course too, don't forget yourself.

You can get paper "certificat d'identite" for under 12 children if they are Belgian residents and not Belgian nationals. They are really simple documents, cost is something tiny like 1.50.  They are a little bit bigger than a credit card and folder over, photo on one side and name on other and parents' details on the back with their telephone number (unusually for Belgium quite a common sense thing). The last time I asked for one for my under 12 year old, the commune official grunted and said she had no idea what I was talking about. Then I produced an expired one and she grunted again and she finally admitted they do exist and made me a new one! Did you meet the same commune official?

I could understand clearly what he asked and I assume he understood my answer too.  We as expats get this ID every year renewed from the commune. For us adults we get electronic cards and for kids (under 12) we get a paper ID card (it is by default provided to us expats as it is our document of permission to stay here - if this card was not given, I am surprised). That (along with the passport - needless to mention in international travel you always need the passport - the question was clear - to travel to India and come back) is a valid travel document for travel to India and back during the validity of that card. The kid's paper resident card is equivalent to adults electronic card (*it basically replaces the visa). That is all I meant.

ID cards are for Belgian nationals only when issued in Belgium.
Expats who are not Belgian cannot get Belgian ID cards.

I am an expat, I have a temporary Belgian ID aka Residence Permit (and I have a national number too) which is renewed every year. After 5 renewals, I get a permanent resident card (again called Belgian ID and I retain my national number).

For me ID is just identification card (whatever identifies you as a resident - be it permanent or temporary). Residence permit card is what we refer to, when we say temporary ID card and it is well understood among us expats. 

And.., Do you have to always negate what I say ?

I think I should stop providing answers in this website.