The Nugget:

Joh 3:13　 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.

The Muslim Challenge:

• If he is fully man, he is bound by time and space. If he is fully God, he cannot be bound by time and space. So if he is both fully man as well as fully God at the same time, then he is both bound as well as unbound by time and space, at the same time.

My Response: As a man born to the Virgin Mary in Bethlehem, Jesus in His human nature was certainly "bound by time and space" until after His bodily resurrection, at which time He possessed what is called a glorified body that was no longer bound by time and space the way we are.   He ascended visibly to heaven after 40 days had passed since His bodily resurrection from the dead on "the third day" (Acts 1:9-11),   Act 1:9 And when he had spoken these things, while they beheld, he was taken up; and a cloud received him out of their sight. Act 1:10 And while they looked stedfastly toward heaven as he went up, behold, two men stood by them in white apparel; Act 1:11 Which also said, Ye men of Galilee, why stand ye gazing up into heaven? this same Jesus, which is taken up from you into heaven, shall so come in like manner as ye have seen him go into heaven.   In His resurrection body, Jesus was able to do things we cannot, like enter a locked room without using the door to enter (John 20:26),   Joh 20:26 And after eight days again his disciples were within, and Thomas with them: then came Jesus, the doors being shut, and stood in the midst, and said, Peace be unto you.   There is an interesting clue in John 3:13 that Jesus as a man was surely bound by time and space to this earth, yet He said He was in heaven at the same time, no doubt said of His divine nature.   Joh 3:13 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.   I have placed the following explanatory note in my book, The New Treasury of Scripture Knowledge, and have retained it in my newest Bible study tool, The Ultimate Cross Reference Treasury:   Some authorities omit this phrase, but its retention may be argued for on the ground that these words may have been dropped out of the text at an early date as superfluous or objectionable (Thomas Whitlaw, commentary on John, p. 69).   That this text is weighty and difficult, is on this very account the more certainly genuine (Scrivener, Introduction, vol. 2, p. 360). While missing from some MSS., it is attested to by the early versions. The text figured early in controversy, including the Apolinarian, and in some instances even the orthodox were reluctant to cite it. The modern counterparts of the ancient Socinian and Arian heresies seem to have a particular attraction to this text. Burgon has shown that it was cited many times by the church fathers. The manuscripts which omit this clause are convicted "of the deliberate suppression of one of the most mysterious, yet one of the most glorious, glimpses afforded to us in Scripture of the nature of the Savior, on the side of His Proper Divinity" (Scrivener, p. 361). Burgon, discussing this passage, notes it teaches that "Christ ’came down from heaven’ when he became incarnate: and having become incarnate, is said to have ’ascended up to Heaven,’ and ’to be in Heaven,’ because ’the Son of Man,’ who was not in heaven before, by virtue of the hypostatical union was thenceforward evermore ’in heaven’" (Causes of Corruption in the Traditional Text, p. 223).   "Hypostatical union" is a term representing Christ as possessing two natures in one Person, human and divine. George Hutcheson explains, "The Son of God hath assumed the human nature into so strict a personal union, that what is proper to either nature is ascribed unto the person under whatsoever name; for, saith he, ’the Son of man which is in heaven,’ which is not to be understood, as if either his human nature came from heaven (for he is speaking of what still is there) or that his human nature were in every place, but that the same person who is the Son of man according to our nature is in heaven according to his divine nature, and yet but one person still" (Commentary, p. 46). God the Son possesses the incommunicable divine attribute of immensity.