Is it permissible to pray for someone who died and only prayed on Fridays, taking into account the fatwa that declares someone who abandons prayer an apostate, whether out of denial or laziness? And is it permissible to pray for someone who deviates from the creed of Ahl al-Sunnah wal-Jama’ah, or to contract a marriage for them? What is the solution if I want to marry a girl whose guardian does not pray?

A person who deviates from the creed of Ahlus-Sunnah wal-Jama'ah is an innovator (Mubtadi'). If his innovation is an act of disbelief (kufr), then a Muslim woman should not be married to him, nor should he be entrusted with performing a marriage contract for himself or for others, nor should the funeral prayer be offered for him when he dies. However, if his innovation is not an act of disbelief, then the funeral prayer should be offered for him upon his death, but it is preferable not to marry him until he repents from his innovation.