A Muslim lady participated in the Hindu holy festival known as 'Holi'.

Answer

The Hindu festival of holi is a ritual of kufr and shirk. A Muslim who participates in holi or who even prefers it becomes a murtad. Participation in any religious custom of the kuffaar expels the Muslim participant from the folds of Islam. Thus, this lady is no longer a Muslim. She has to repent, renew her Kalimah, and if married, have her Nikah renewed. The following episode is interesting and fearful: In India there was a great Aalim who was walking in the street on the day of the Hindu Holi festival when they splash coloured water and perhaps coloured cow urine on every person who crosses their path. This Aalim passed by a donkey. In an idle moment, not thinking seriously, the Aalim who was chewing paan (beetle leaf) at the time, addressed the donkey and said: "Everyone is happy and splashing coloured water on everyone, but no one is splashing anything on you. Come, I shall splash coloured water on you." So saying, he spat on the donkey his saliva which was red as a result of the paan.

After this Aalim had died, a Buzrug saw him in Jahannum in a dream. When the Buzrug in his dream enquired why he was being punished in Jahannum, he (the Aalim) narrated the episode of the donkey and said that Allah Ta'ala's Wrath overtook him because he had emulated a custom of shirk/kufr even though without intention of kufr.

It is haraam to even jocularly imitate practices of kufr and shirk. Rasulullah (sallallahu alayhi wasallam) would make dua: "O Allah! I seek refuge with You from an evil moment and an evil friend." The Aalim was a victim of an 'evil moment'.