“But the hour cometh, and now is – The old dispensation is about to pass away, and the new one to commence. “Already” there is so much light that God may be worshipped acceptably in any place.
The true worshippers – All who truly and sincerely worship God. They who do it with the heart, and not merely in form.
In spirit – The word “spirit,” here, stands opposed to rites and ceremonies, and to the pomp of external worship. It refers to the “mind,” the “soul,” the “heart.” They shall worship God with a sincere “mind;” with the simple offering of gratitude and prayer; with a desire to glorify him, and without external pomp and splendor. Spiritual worship is that where the heart is offered to God, and where we do not depend on external forms for acceptance.
In truth – Not through the medium of shadows and types, not by means of sacrifices and bloody offerings, but in the manner represented or typified by all these, Hebrews 9:9, Hebrews 9:24. In the true way of direct access to God through Jesus Christ.
For the Father seeketh … – Jesus gives two reasons why this kind of worship should take place. One is that God sought it, or desired it. He had appointed the old mode, but he did it because he sought to lead the mind to himself even by those forms, and to prepare the people for the purer system of the gospel, and now he sought or desired that those who worshipped him should worship him in that manner. He intimated his will by Jesus Christ.”
Hebrews 9:9 – Which was a figure for the time then present, in which were offered both gifts and sacrifices, that could not make him that did the service perfect, as pertaining to the conscience.
Hebrews 9:24 – 26 For Christ is not entered into the holy places made with hands, which are the figures of the truth; but into heaven itself now to appear in the presence of God for us: Nor yet that he should offer himself often, as the high priest entereth into the holy place every year with blood of others; For then must he often have suffered since the foundation of the world: but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself.
Resource: Barne’s Commentary