Taqiya, or not showing their faith openly by means of pretense, dissimulation, or concealment, is a special type of LYING which is taught and used by Muslims.
taqiy "Taqiya" (or taqiyyah) is related to the terms "taqwa'" and "taqi'" - all have the root meaning of "guarding" something, in this case, the Islamic faith.
"Hamas: We’re Allowed to Lie," from Israel National News :
(IsraelNN.com) Hamas leaders spoke to the Arabic language Ash-Sharq il-Awsat newspaper recently and explained that as Muslims, they are allowed to lie. In an interview printed on Thursday, senior Hamas terrorists explained, “A Muslim is permitted to say things that oppose his beliefs in order to prevent damages or to be saved from death.”
This approach, known in Arabic as “taqiyya,” was behind several Hamas leaders’ recent public expression of support for Palestinian Authority Chairman Mahmoud Abbas, they explained. Senior Hamas terrorists in Samaria, who were recently released from jail, publicly expressed disapproval with the Hamas takeover of Gaza and said they supported the PA forces. The sources quoted in Ash-Sharq il-Awsat explained that the Samarian terrorists’ announcement was not a sign of dissent within Hamas ranks, but rather a permitted use of “taqiyya” to deceive Abbas and avoid prison sentences.