Certainly, dissimulation (Tayiqqah) is our religion but it is important to know where to practice Taqiyyah. His Eminence Imam Sadiq (peace be upon him) says:
“Certainly, dissimulation (Taqiyyah) has been kept so that blood is protected but if despite dissimulation (Taqiyyah) blood is split (life cannot be protected), then there is no (need for) dissimulation (Taqiyyah).”
“By Allah! If we call you for helping us, you will say ‘we will not do so because we are practicing dissimulation (Taqiyyah) and this dissimulation (Taqiyyah) is dearer to you than your fathers and mothers…”
[Tahzeeb al-Ahkaam, vol. 6, p. 172, H. 335]
Imam Ali Ibn Moosa al-Reza (peace be upon him) refused to meet some people who had claimed to be Shias by saying:
“As for your claim that you are the Shias of Ameerul Momineen (peace be upon him) … you defy him in most of your actions, fall short in many of your obligations, belittle the greatest rights of your brothers in faith, you practice dissimulation (Taqiyyah) where there is no obligation it and forsake it where it is necessary to practice it.”
[Tafseer Imam Hasan Askari (a.s.), p. 313, H. 159; Al-Ehtejaaj, vol. 2, p. 441]
Hence, according to these traditions, dissimulation (Taqiyyah) is not permissible when it comes to supporting Ahlul Bait (a.s.) and defending their rights.