When the Jews asked the Lord for a “sign” (2:18), they were looking for a miraculous sign, the kind the Jews require (I Cor.1:22). Sometimes Gentiles scoff at the Jews for requiring a sign, but God taught them to look for signs, right from their beginning as a nation. When Moses feared Israel would not believe God had spoken to him (Ex.4:1), God gave him the power to handle serpents (4:2-5 cf. Mark 16:18) and the power of healing (Ex.4:6,7 cf. Mark 16:18). So the Jews in John 2 were not unspiritual to ask for a sign.
The Lord responded by saying, “Destroy this temple, and in three days I will raise it up” (John 2:19). Here it helps to remember that they were still standing near the temple He had just cleansed, so the Jews thought He spoke of the building (2:20). Of course, He spoke “of the temple of His body” (v.21), but why would He call His body a temple? Well, a temple is a building in which a god lives, and that certainly describes the Lord’s body! Now while the Jews misunderstood His words, they never forgot them. Of course, they twisted them (Mark 14:55-58). He had said that if they destroy the temple, He would raise it up, but they accused Him of saying that He would destroy the temple, making Him guilty of being against the temple
The Lord could have avoided this confusion by simply pointing to Himself while speaking of the temple, so why didn’t He? It is almost as if He didn’t want to give them a sign. Why not, if they weren’t unspiritual to ask for one? And it wasn’t the only time He refused to give them a sign. He refused to give them a sign in Matthew 12:38-40 because He’d just given them one (v.22). This is why He called them an “adulterous generation” (v.39). Once you commit adultery you always want more. So when they asked for another miracle, the Lord told them the only other one He’d give them was that of His resurrection (Mt.12:39,40). And when they asked for another miracle in John 2, right after the Lord had turned water into wine and cleansed the temple, a miraculous feat for one man to perform, He again said the only other miracle He’d give them was the miracle of the resurrection (2:20).
As we’ve seen, the Jews didn’t understand His words, but neither did the disciples—until later (2:22). That’s the thing about Bible prophecy, it is often unfathomable until it happens, but once it happens, it is clear to see. So don’t be discouraged if you don’t understand prophecy! It’s all about Israel anyway, so you don’t have to understand it. You have to understand Paul’s epistles, for they are written to you!
Next, why wouldn’t the Lord commit Himself to people who believed on Him (John 2:23,24)? This is an important question for all of us who have believed on Him! And there are a couple of answers to this question.
First, the Lord did not commit Himself to them “because He knew all men” individually (v.24), i.e, knew them personally without having met them, as He showed in John 1:42 and John 1:47-49. And so He knew these “believers” had not believed “to the saving of the soul” (Heb. 10:39).
Next, He “needed not that any should testify of man” (John 2:25), i.e., of men in general. He knew we tend to believe when we see a miracle, and that’s a problem. You see, while God taught Israel to require miraculous signs, He never told them to believe only because of miraculous signs. Pharaoh’s magicians were able to work miracles, and Antichrist will work them also. Israel was supposed to believe a man was sent from God only if the message He preached was according to God’s Word (Deut. 13:1-3).
Finally, notice that these people “believed in His name” (John 2:23). This sounds like what we do today to be saved, but it isn’t. During the Lord’s earthly ministry, they had to believe that He was the Christ to be saved (John 6:68,69; 8:24; 9:35-38; 11:27; 16:27,30,31; 17:8; 20:31). Nor did this change at Pentecost (Acts 2:36). The Lord’s “name” was Jesus Christ, and to be saved under the kingdom program, all you had to believe was that He was the Christ, i.e., have faith in His name. While that is a good start today, it is not enough to be saved. Today you have to have “faith in His blood” (Romans 3:25). An important dispensational difference, one with eternal consequences!