December 3

…the House of Justice advises the Bahá'ís to maintain a balance between their adherence to the Cause and obedience to its laws on the one hand, and their role in society on the other. When an individual becomes a Bahá'í he acquires, as you are aware, a wider loyalty to the Manifestations of God. Having found this new way of life, he should be careful not to isolate himself from his family and his people, and he should show respect for his former religion. The Bahá'ís should, of course, avoid performing any acts which could be considered as implying their membership in another religion or which are contrary to Bahá'í principles. There is a clear distinction between participating in festive and cultural events, as opposed to performing religious ceremonies and rituals. 
- The Universal House of Justice  (From a letter dated 26 May 1982, written on behalf of the Universal House of Justice to a National Spiritual Assembly; The Compilation of Compilations, vol. III, Cultural Diversity in the Age of Maturity)