There are three things to consider when we talk about meat to be halal for consumption: 1) tazkiya (draining of blood at the time of slaughtering) 2) tasmiya (reciting Allah’s name at the time of slaughtering) and 3) Tasmiya to be done by a person who believes in God and does not originally subscribe to polytheism. In Ghamidi sahab’s view all are absolute requirements. However, in Imam Shafi’s view, while tazkiya is still a requirement, tasmiya is a sunnah that if one doesn’t perform, the meat is still halal. (Please see: Discussion 76161 • Reply 76181)

Christians and Jews of that time used to invoke God’s name, used to perform Tazkiya and originally subscribed to monotheism, therefore, their Zabiha was declared Halal. In today’s time, since Christians do not fulfil requrements of Zabiha intentionally after they abrogated the Sharia, therefore their meat would not be Halal. Jews on the other hand, fulfil all the requirements of Zabiha meat, so their meat would be considered Halal unless some explicit evidence points to the contrary. This is the viewpoint of Ghamidi Sahab.

Please refer to the video below from 1:48:11 to 1:50:36

https://www.youtube.com/live/1Yg42iePNwo?feature=share&t=6491

Please also refer to the following comments of Ghamidi Sahab from 39:04 to 39:47

https://youtu.be/RiXYdvVgM8w?t=2344