In a recent anti-LDS volume from a Reformed perspective, we find the following attempted defence of the Trinity:
In a further response to rationalist critics of God’s triune nature, Geisler says:
Critics make a point of computing the mathematical impossibility of believing there is a Father, Son, and Holy Spirit in the Godhead, without holding that there are three gods. Does not 1+1+1=3? It certainly does if you add them, but Christians insist that the triunity of God is more like 1x1x1=1. God is triune, not triplex. His one essence has multiple centers of personhood. Thus, there is no more mathematical problem in conceiving the Trinity than there is in understanding 1 cubed (13).
Norman L. Geisler, Baker Encyclopedia of Christian Apologetics, 732 as cited by Jack Kettler, The Religion that Started in a Hat: A Reference Manual for Christians Who Witness to Mormons, p. 192
The trite formula 1x1x1=1 to support the Trinity is utter nonsense, and it really is illogical to the nth degree. Fortunately, more informed Trinitarian apologists never use it. The following video explains very well why this formula is simply nonsense:
