What is meant by sealed hearts?

What is meant by sealed hearts?

According to the common understanding Allah seals the heart of those, He wants. Therefore, the people whose heart is sealed cannot believe anymore.
However, according to the Quran the heart of the person is sealed temporary due to the disbelief of the person, not because of Allah’s wish. Thus the sealing of a heart doesn’t happen for no reason or groundlessly. It happens as a result.
Traditionally in the mind there are some reasons for sealing a heart, for example not going three consecutive times to Friday (Jumua) prayer without an excuse. The reasons for sealing the hearts in the Quran are:
* Denying the Quran (al-Baqara 2:7; Muhammad 47:16; Ghafir 40:35; al-Munafiqun 63:3; an-Nahl 10:74).
* Say a pretext (at-Tawba 9:86-87) or lying (at-Tawba 9:93) for not joining the jihad [Struggle and strive for Allah’s sake].
The most remarkable verse about this topic is this:
“… In fact, God has sealed them for their disbelief, so they do not believe, except for a few!” (Quran, an-Nisa 4:155. Also al-Baqara 2:88; al-Jathiya 45:23).
Therefore, the temporary seal depends on a person’s own behaviour. However, the possibility of belief always exists. Anyway, the opportunity of repentance (istigfar) exists while the person is alive (al-Anam 6:158). The permanent seal will be affixed when the human dies.