Chivalry: 2. The qualifications of a knight, as valor, nobility, fairness, courtesy, respect for women, protection of the poor, etc.
3.The demonstration of any of the knightly qualities.
Source: Webster’s Unabridged Dictionary.
There were approximately five definitions listed. None mentioned christianity.
Since we are Americans, it seems to me that the definition in Webster’s is more relevant to us than the one in Oxford’s.