William G. T. Sheed (1820-1894) noted the problematic nature of translating πνευμα in John 4:24 as "a spirit" in light of Trinitarian theology:
God’s Spirituality
The words of our Lord to the
Samaritan woman, “God is a Spirit” (John 4:24), although spoken for a practical
purpose, are also a scientific definition. The original (pneuma ho theos) by
its emphatic collocation of pneuma and omission of the article implies that God
is spirit in the highest sense. He is not a spirit, but spirit itself,
absolutely. The employment of the article in the English version is
objectionable, because it places the deity in a class with other spiritual
beings. But this is not the thought of Christ, who asserts that “no
one knows the Father but the Son” (Matt. 11:27), thus claiming for himself a
knowledge of the deity as the absolute and unconditioned spirit, who is not
cognizable by the finite mind in the manner and degree that finite spirit is.
Man knows the nature of finite spirit through his own self-consciousness, but
he knows that of the infinite spirit only analogically. Hence some of the
characteristics of divine nature cannot be known by a finite intelligence. For
example, how God can be independent of the limitations of time and have an
eternal mode of consciousness that is without succession, including all events simultaneously
in one omniscient intuition, is inscrutable to man because he himself has no
such consciousness. The same is true of the omnipresence of God. How he can be
all at very point in universal space baffles human comprehension, though it has
some light thrown upon it by the fact that the human soul is all at very point
in the body. (William G. T. Shedd, Dogmatic Theology: Complete and
Unabridged, Volumes 1-3 [Reformed Retrieval, 2021], 113, emphasis in bold
added)
On John 4:24 itself, see:
Lynn Wilder vs. Latter-day Saint (and Biblical) Theology on Divine Embodiment