AtmA

It is somewhat difficult to make exact suggestions because it lacks context. Please see whether one of the above proposal serves your purpose.

--------------------------------------------------
Note added at 48 mins (2006-08-04 18:20:15 GMT)
--------------------------------------------------

As mentioned by me above, the context is lacking. Spirit also means a state of a person's emotions. If this is the case, it could be translated as follows because it concerns the field of advertisement:

बहादुरी का जोश-----BahAduri kA josh



--------------------------------------------------
Note added at 54 mins (2006-08-04 18:26:04 GMT)
--------------------------------------------------

ताकत का जज़्बा---tAqat kA jazbA

other terms:

विशाल हृदय, उदात्तता, उदारमना, महानुभाव, दुर्बलरक्षक, पतितपावना, दीन-ए-इलाही

Usually in English chivarly is targetted mainly at the weaker sex, so the last three may not be too appropriate, though they are dictionary equivalents of chivalrous.

In this sense अबला रक्षक may be considered a coined equivalent of chivalrous in Hindi.

But however, the best equivalents in my opinion is उदात्तमना or उदारमना.

chivalrous spirit- mahaan aatmaa, vishaalhridyee aatmaa