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 are not aware of any evidence about this in the statements of the scholars . The Two Testimonies of Faith being linked together do not require from a Muslim to suppose things which do not exist. We do not know from where you got this, that a man has two brains and two livers. Indeed, the textual evidence [from the Quran and the Sunnah of the Prophet ] and the logic about the Oneness of Allaah are so many, as well as about the truthfulness of the Prophecy of the Prophet Muhammad . For more benefit, please refer to Fataawa 85461 and 85755.
However, it is more proper for a Muslim to learn the meaning of these Two Testimonies of Faith and act according to them by singling out Allaah alone for worship and by adhering only to the way of the Prophet .
As regards trinity, then this concept is void in principle and it contradicts the religious texts and logic. This is based on exaggerating in extolling the Prophet, ‘Eesa (Jesus) and raising him to the level of being a God. If one follows this way, he imitates the Christians in a matter that is void in principle. What is worse is that this may even lead to extolling our Prophet in the same way they did with their Prophet .
It is in this context that the Prophet warned us against this saying: ''Do not extol me as did the Christians extol ‘Eesa the son of Mary, may Allaah exalt their mention; I am only a slave, so say ‘the Slave of Allaah and His Messenger’.’’
For more benefit on the falseness of the trinity, please refer to Fatwa 84277.
Finally, it should be mentioned that it is better for a Muslim to preoccupy himself with what benefits him with regard to his religion and his worldly matters; it is enough for him to follow in the footsteps of the Salaf (righteous predecessors) and the former scholars of this nation and to adhere to their way of understanding Islam.
Allaah Knows best.