This is completely a natural behavior of all living creatures of Allah. Have you not seen how many animal whodon’t have strong body and can’t defend themselves change their skin color or those who are strong enough according to the situation change their strategy and either save their life or attack other animals. This we call nature in our general discussion so what about human who despite our intellect and wisdom if in any situation or circumstances if we stuck and face problem and we know this is not going to harm whole humanity nor whole society for example some mischievous people find you alone and say that “ say there is no God otherwise I’ll kill you” Now if I have strong faith in my Heart that there is only One God and He is Allah but if we say just by tongue that there is no God and save our life did I do wrong? No my faith is inside my heart but at this moment I have to save my life. But if the same situation come publicly and I know if I deny Oneness of Allah many people will loose their faith then now it’s haram to hide your faith and do taqaiyyah. Now I have to announce publicly that yes there is One God and if they kill me let them kill. What Imam Husain (a.s) and other our Aimmah (s.a) they did.
But Taqaiyyah is very clear and based on logic and those who deny strongly this act they also do it every day and hundreds of times in their life because it a natural phenomenon. Make sure telling lies and Taqaiyyah is different from each other. Taqaiyyah is the need of nature while lying is against the nature. That is why if you ask a five old child you like if someone tell you a lie he will say no but if you ask if someone want to harm you what will you do, he will say I’ll ran away and this running away to save your life is called as Taqaiyyah.