Shaykhul Islaam Ahmad ibn Taymeeyah 728AH (May Allah have mercy on him) said,

ﻣﻦ ﺗﻜﻠﻢ ﻓﻲ ﺍﻟﺪﻳﻦ ﺑﻼ‌ ﻋﻠﻢ ﻛﺎﻥ ﻛﺎﺫﺑﺎً، ﻭﺇﻥ ﻛﺎﻥ ﻻ‌ ﻳﺘﻌﻤﺪ ﺍﻟﻜﺬﺏ

“Whoever speaks about the religion without knowledge is a liar even if he doesn’t intend to lie.”

Source: Majmu’ Fataawa 10/449