Are all spiders poisonous?

No. Very few are.

No not all spiders are poisonous.. But theer are some spieces which can be life taking..

the ones commonly found in india are non-poisonous.

No, on the contrary, very few are. And I don't think any of them are found in India (where I assume you live going by your name). If you are worried about those web-spinners in your room then fear not. It only douses its prey in enzymes to digest it BEFORE ingestion! I think you should be more worried about them damn bloodsucking mosquitoes which are carriers of deadly illnesses. Ciao.

i dont think all spiders are poisonous

they are non poisonous spiders out there. they have other self-defense mechanism such as super high jumps or camouflage.