First of all +"God is Spirit."+ This we read in our first text: John 4:24, +"God is Spirit."+ You will note that in your Bible, both the Authorised and Revised Versions, you read, +"God is a Spirit."+ But there is no indefinite article in the Greek language, and wherever it is necessary in the English translation to fit the English idiom, it has to be supplied, and it is supplied, in this case. But there is really no reason for supplying it here any more than there is for supplying it in 1 John 4:8 and translating, +"God is a Love,"+ or in 1 John 1:5 and translating +"God is a Light."+ The preferable translation is as I have given it: +"God is Spirit."+ This is a definition of the essential nature of God. What does it mean? Our Lord Jesus Himself has defined what is meant by "spirit" in Luke 24:39, where He is recorded as saying after His resurrection: +"See My hands and My feet, that it is I Myself; handle Me, and see, for a spirit not flesh and blood, as ye behold Me having."+ It is evident from these words of our Lord that _spirit_ is that which is contrasted to body. That is to say, spirit is incorporeal, invisible reality. To say, "God is Spirit" is to say that God is essentially incorporeal and invisible (cf. 1 Tim. 6:16), that God in His essential nature is not material but immaterial and invisible, but none the less real. This thought is also found in the very heart of that revelation of Himself which God made to Moses in the first division of the Old Testament. For example, we read in Deut. 4:15-18: +"Take ye therefore good heed unto yourselves; for ye saw no manner of form on the day that Jehovah spake unto you in Horeb out of the midst of the fire; (16) lest ye corrupt yourselves, and make you a graven image in the form of any figure, the likeness of male or female, (17) the likeness of any beast that is on the earth, the likeness of any winged bird that flieth in the Heavens. (18) The likeness of anything that creepeth on the ground, the likeness of any fish that is in the water under the earth."+ This is a plain declaration way back fifteen centuries before Christ, of the _spirituality_ of God in His essential nature. God is essentially invisible spirit.
But it is also clearly revealed in the Word of God that "spirit" may be manifested in visible, bodily form. We read in John 1:32 these words of John the Baptist speaking about what his own eyes had seen: +"And John bore witness, saying, I have beheld the Spirit descending as a dove out of heaven; and it abode upon him."+ Here, then, we see Him who was essentially spirit manifesting Himself in a bodily, visible form.
Furthermore in the Bible we are told that God has manifested Himself in visible form. We read in Ex. 24:9, 10: +"Then went up Moses, and Aaron, Nadab, and Abihu, and seventy of the elders of Israel: (10) and they saw the God of Israel; and there was under his feet as it were a paved work of sapphire stone, and as it were the very heaven for clearness."+
What they saw was not God in His essential nature as Spiritual Being. Indeed, what we see when we see one another is not our essential self, but the house we live in, and so John could say, as he does say in John 1:18: +"No man hath seen God at any time."+ And so I could say to you now that you do not see me. Nevertheless, it was a real manifestation of God Himself that they saw, and so it could also be said, and said truthfully, that they had seen God, as it could be truthfully said, "you see me."
Furthermore still, though God is essentially spirit, God has a visible form. This is taught in the most unmistakable terms in Phil. 2:6, where we are told of our Lord Jesus that He existed originally "in the _form_ of God." The Greek word which is translated "form" in this passage means "visible form," "the form by which a person or thing strikes the vision," "the external appearance." It cannot mean anything else. This is the definition given in the best Greek-English lexicon of the New Testament, of the word here translated "form." Now as Jesus existed originally "in the form of God," it is evident that God Himself must have a form, this form in which our Lord Jesus is said to have existed originally.