All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
We have already issued many Fataawa regarding the ruling on a person who abandoned and neglected the prayer either by rejecting its obligation or out of laziness. You may refer to Fatwa 84235.
It is known that there are three things which prevent a person from inheriting others; they are slavery, killing [the inherited person], and the difference of religion. Details on these matters could be found in the books of Fiqh.
The ruling about inheriting a person who abandons the prayer out of laziness is based on the difference of opinion among the scholars about him being a Muslim or a non-Muslim. The majority of the scholars who are of the view that whoever abandons the prayer out of laziness is not a non-Muslim, are of the view that it is permissible for him to inherit because he is a Muslim unless there are other impediments that prevent him from inheritance, and they are slavery and killing. So a slave does not inherit and a killer does not inherit the person he killed. However, the scholars who are of the view that whoever abandons the prayer out of laziness is a non-Muslim, are of the view that it is not permissible to inherit a non-Muslim as there is an impediment of inheritance, which is the difference of religion. Moreover, there are some differences of opinion amongst them [scholars] with regard to defining the "difference of religion.”
To conclude, the issue of whether a person who abandons the prayer out of laziness inherits or not, and whether he may be inherited or not, is something on which there is a difference of opinion amongst the scholars as regards whether he is a Muslim or a non-Muslim.
It is only an Islamic court which may decide about such an issue as it is the body which is appointed and entrusted to rule regarding such matters.
Allaah Knows best.