I have heard it taught that as one dispensation passes away and the next one comes forth, that somehow those dispensations can and do "meld together." Now "spiritually speaking" I can understand a certain aspect of that thinking. That is to say the Bible does teach us that things are brought forth in the spiritual (heavenly) realm before they come forth in the natural (earthly) realm. However that principle –although true– is another matter altogether and we want to compare apples to apples here.
Now some will say since Jesus ministered while the "dispensation of the Law" was still in effect, that this in some way proves "the Law" overlapped into "the Church age" and visa versa. Nevertheless the "indwelling" presence of the Holy Spirit was not given to the Church "corporately" (John 7:39, 14:17) until "after" Jesus resurrected and was glorified (John 20:22), which after all is the very essences of the dispensation of Grace. Furthermore what Jesus was sent to fulfill the scriptures, which obviously needed to take place within the Old Testament timetable. Keep in mind it was Jesus Himself who told the one leper to "Go thy way, show thyself to the priest, and offer the gift that "Moses" commanded for a testimony unto them" Matthew 8:4. Therefore Jesus Himself acknowledged He was still operating within the confines of the dispensation of the Law at that time. Jesus knew He was to close out the Old Testament by finishing the work of atonement, and yet "point the way" to the New Testament (the work of the Church age as enabled by the Holy Spirit & grace) which could only have began "corporately" at the spiritual fulfillment of Pentecost (Acts 2:1). Now one might argue that grace or the Church age started when the first Apostles received the Holy Spirit as mentioned above in John 20:22. Just the same that administration still took place "after" the three and one half years (42-months) of Jesus' ministry and resurrection. In that instance though the Apostles were shown "in type" to be the first of the first fruits (Ex 23:19), but the limited giving of the Spirit in that instance was still well after Jesus had finished ("it is finished" John 19:30) His primary mission. Jesus said in John 12:27, "Now is my soul troubled; and what shall I say? Father, save me from this hour: but for this cause came I unto this hour" [to become the actual Lamb of GOD and atone for sin]. Thus the dispensation of "the Law" would have already been closed out before the Spirit was available to the Church.
Apparently the "overlap" doctrine believers want to equate Jesus' ministry (His miracles, teachings, and showing forth of mercy) as the start of the Church age and grace. Yet at the same time the Law proper was still being observed –even by Jesus Himself. I believe most of the confusion with this doctrine comes simply from not fully understanding what constitutes each dispensation. As previously stated the fact that Jesus performed some miracles and taught on the grace of God did in no way "begin" the dispensation of grace. What began the time period we call "grace" was when the Holy Spirit was given to the Church. Which means the actual moment the "third temple/the Church age" was first corporately recognized or as Acts 2:1 says, "was fully come," was when the tongues of flame alighted on the heads of those in the upper room. So what I am saying here is this, there can be a "prophesying" and even a foretaste of what the next dispensation has in store, but there are exact points (events) mentioned in the Bible that clearly distinguish the beginning and end of these time periods or dispensations; that is if you know what you are looking for.
There is yet another thought to consider in this matter concerning dispensation parameters and that is this, most everything Jesus did while He ministered had already been done in like manner by many of the Old Testament saints and prophets. Or should we say that "the dispensation of grace" started when the "manna fell," the "red sea split," or people were "healed" by the word of the prophet? How about when Elisha raised the Shunammite's son "from the dead" in 2-Kings 4? Then there are all the teachings, prophesies, and psalms proclaiming God's love, and yes, even "the grace" and mercy He would extend towards the Gentiles and His own backslidden people. Now the fact remains those events took place hundreds and thousands of years before "Pentecost was fully come." As a matter of fact, during "the dispensation of the Law" the LORD GOD had also (just like Jesus) proclaimed the "new covenant" He would make with all nations through His Son's blood, like in Jeremiah 31:33-34.
You will also learn that the Bible has given us certain parameters by which we can define and identify these dispensations and time-periods so we could know "the time of our visitation" (see Luke 19:44 below). If this was not true nobody would know what "signs of the time" to watch for as we are commanded to do. Our GOD is not a God of confusion; He does not promote "fuzzy math," that is when it comes to "knowing the time." He has provided the understanding to many of the prophetic time periods and what was hidden was to be released at the "time of the end," the time we are now walking in:
"In the first year of his reign I Daniel understood by books the number of the years, whereof the word of the LORD came to Jeremiah the prophet, that he would accomplish seventy years in the desolations of Jerusalem." Daniel 9:2
"[Jesus speaking] And shall lay thee even with the ground, and thy children within thee; and they shall not leave in thee one stone upon another; because thou knewest not the time of thy visitation." Luke 19:44
"WATCH ye therefore, and pray always, that ye may be accounted worthy to escape all these things that shall come to pass, and to stand before the Son of man." Luke 21:36
"But know this, that if the goodman of the house had known in what watch the thief would come, he would have WATCHED, and would not have suffered his house to be broken up." Matthew 24:43
"So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation." Hebrew 9:28
Therefore there must be a way provided for the diligent seeker to "know the time," and for sure "the dispensation" that they find themselves in. As a matter of fact the most crucial time of any dispensation has always been shown to be at the beginning and or end thereof. Thus if we were meant to "over-lap" or "shift" the beginning and end of these dispensations (one on top of the other) it could only result in confusion and much error, even for those who were and are diligently seeking their place of readiness before GOD. Nevertheless no matter what you believe "over-lapping" cannot change the prophesied divine order of events that must happen during each of these time periods. In other words we cannot honestly say the "seventh millennium" has already started (some believe in AD 2000) when "none," and I repeat "none" of the events that signify the start of that dispensation have begun. Case in point, the "judgment seat of Christ," the "thousand year reign" of the overcomers, "Satan bound," etc. Moreover some of the events the Bible tells us must happen before the end of the Church age (see: link #1, link #2, link #3), have not come to pass yet. Things like the "42-month" ministry of the Two Witnesses during "the great tribulation," the "Witnesses' death and resurrection," and "Armageddon" just to name a few.
In like manner the "days of creation" (which correspond to seven millenniums) had definite beginning and ending points. That is, God stated what He made in each day of creation, then afterwards that day was considered done or finished before the next day could begin. This would mean that "symbolically" God must finish "making" the things that are appointed to be made or brought forth (like spiritual revelation) in each millennium and that includes the sixth millennium. So essentially the sixth day, the day in which the man and "the beast" were created, must be allowed to come to its fullness (666: the fullness of the beast nature) before it can end. If you remember the "sixth day" was also the day in which the "double portion" of manna was given (Ex 16:22); it was not given in the seventh day. That same double portion represents symbolically the giving of the "former and the latter rain" anointing (Jer 3:3; Hos 6:3; Joel 2:23) to the Witnesses. This premise is clearly explained in the "Six days of Creation page." The other obvious problem with over-lapping the different dispensations is that the end of each dispensation has to then over-lap into the next and the next and so on; and who is the one that determines by how much they overlap and when? Keep in mind if the dispensations were to truly over-lap in any tangible sense then what happens at the end of one dispensation or time period should be happening "at the same time" that the beginning events of the next dispensation are taking place, and the Bible and history simply does not show us this mixing or over-lapping of events in type or otherwise.
Lastly, it has been stated by some in the body do understand types that the seventh millennium must start in the evening (in spiritual darkness or what the Bible calls "midnight") before "the light" can come forth. They say this because the natural Jewish day starts at sundown. That premise is at best an error caused by not knowing the Word pertaining to the dispensations. Part of what fuels this unscriptural belief is that God had (up to this point) always equated each new day in Genesis to start with the "'evening," but they forget the seventh day is unique (see link). So to foster this false belief they have to believe they can equate "night" to the seventh day, just as it was with the first six days of creation; days which did start with the evening. However "the Bible" does not apply the statement "evening and morning..." to the seventh day in Genesis. As a matter of fact "the Bible" tells us there will be "no night" (spiritually speaking) in the seventh millennium, so how can it then start off in a time of spiritual darkness like the great tribulation?
"And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honour into it. And the gates of it shall not be shut at all by day: for there shall be no night there." Revelation 21:24-25
"And there shall be no night there; and they need no candle, neither light of the sun; for the Lord God giveth them light: and they shall reign for ever and ever." Revelation 22:5
No my friend, we are still in the sixth millennium or at least in a time like Joshua 10:13 says where the sun stood still for a whole day. Or maybe we are experiencing "the extra time" that the "Good Samaritan" said he would "repay" upon His return in Luke 10:35, which is symbolically after the "two pence" (two thousand years of the Church age) had been used up? Either way brethren, "a thousand years is still a thousand years"; the seventh millennium is not cut short in the Bible. Satan must be bound "a thousand years." The saints must rule and reign "a thousand years." The remaining dead must stay dead after the judgment seat of Christ another "thousand years" before they rise to their judgment. We must believe the Word in these matters brethren, not some man made calendar which we know is off. Unfortunately there will always be those that believe the Bible does not mean a literal "one thousand year seventh millennium" is going to occur even though Revelation 20 alone mentions this thousand year span "six times." Friends do not be like "lemmings to the slaughter."
Do not allow yourself to become "bewitched" by the multitude of traditionalist who only preached what they were told and never sought these truths out for themselves.