There are some people who are weak minded and are weak when he doubts are thrown at them. My question is how to become strong minded and make our hearts like a glass which can see the doubts but it cannot enter it . What books we should study so that we are safe from all doubts?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Protecting oneself from misconceptions and doubts can be achieved through the following:

Firstly, taking refuge in Allah Almighty and asking His protection against them. A Hadeeth reported by At-Tirmithi reads: "Indeed the hearts are between two of the Fingers of Allah, He fluctuates them as He wills." Therefore, he who takes refuge in Allah Almighty by supplicating Him, Allah will protect him against afflictions.

Secondly, one can protect himself against misconceptions and doubts by seeking Islamic knowledge. Knowledge is a light that removes the falsehood and misconceptions.

The way to attain Islamic knowledge is by reading and understanding the Book of Allah (i.e., the Quran) and the Sunnah of the Prophet at the hands of the scholars who are well-versed in knowledge. The greater one's knowledge is, the farther he becomes from being affected by falsehood.

Thirdly, a person can protect himself against misconceptions by staying away from listening to them and to those who promote them and by being cautious from reading them. The Prophet ordered the one who would be present (alive) at the time of the Dajjaal (Antichrist), to stay away from him. He said: "Let him who hears of the Dajjaal stay far from him, for I swear by Allah, a man will come to him thinking himself to be a believer but (eventually) follow him (the Dajjaal) because of confusion the Dajjaal cause him to have (about faith)." [Abu Daawood] Ibn Al-Qayyim said in 'Uddat As-Saabereen: "I know of no better way of ridding evil than staying away from its causes, and its sources." [End of quote]

Allah Almighty Knows best.