Moshiach, Mahdi, Kalki, Christ, Maitreya are actually different names and titles of the exact same person - the Moshiach Ben David who has come as the Avatar of the New Age, not just for any specific religious group but for all men. But this is definitely NOT the End of the World. Far from it being the end, it will be a whole new glorious beginning.
Many Christians believe Jesus will return at the end of the world to take the faithful Christians to heaven in a 'rapture'. Why would God favor Christians over the other 4-5 billion humans - also his children? Why would a 'loving' God allow the world to be destroyed? - it is silly to believe all this. Actually Jesus will indeed return, but the rest of the story is completely untrue.
Muslims believe the Imam Mahdi will return as an Arab and lead the Muslims to victory over the unbelievers. Why would God favor Muslims over the other 4-5 billion humans? What is so special about Arabs?- it is just as silly to believe that.
Jews believe Moshiach will come and establish a Torah government in Israel which will be the center of the world. Jews may think they are 'chosen', but nobody can seriously believe that G-d prefers them to all the rest of humanity.
If God sends a Messiah, he will send one for all of humanity - Jews, Christians, Muslims, Hindus, Buddhists alike. He will definitely not favor any one group over the other. To believe this is to be deluded by a false sense of superiority (racial or religious) or of being more spiritual or righteous than other people - this is just not true - all individuals and groups are special in their own way, but definitely not more special than other groups.
Benjamin Creme of Share International has been speaking about the imminent open emergence of the Messiah to the every day world for several years now. In December 2008, Creme revealed that the coming of Maitreya would be heralded by the appearance of a star in the sky (similar to star that preceded the birth of Jesus). In 2009, thousands of people saw the star in sky in multiple location. In 2010, the emergence of Maitreya has finally occurred at last. On February 14th, Creme announced that Moshiach or Maitreya had made his first open appearance and given an interview on an American TV show. Since that time, Moshiach has appeared on the same channel at least forty more times (He has also given several interviews on a channel in Mexico, many in Brazil, after that in Russia and now in China). He has come incognito without identifying himself as the Messiah. According to Creme, "He spoke earnestly of the need for peace, achievable only through the creation of justice and the sharing of the world's resources."
Some of the consequences of Moshiach's open presence in the world:
The spiritual level of the world will rise considerably - this also means unjust institutions, organizations, regimes will have difficulty surviving. The unjust, capitalistic financial and economic world order will be one of the first things to collapse. Undemocratic, dictatorial governments like China, North Korea, Burma, Iran will have to change.
The resolution of karma (individual, group, national karma), will accelerate. This may mean natural disasters (earthquakes, storms, floods etc) or even man-made ones for areas which need to be cleansed of their bad karma (like Israel, Pakistan, USA, China etc).
Even in your personal life, if you have been getting away with murder (figuratively speaking of course), that will probably end presently. Expect any free rides or any situations where you have been able to take advantage of others (or you have been taken advantage of), to end soon.
A major effect will be a stark division amongst all people - those who accept and respond positively to Moshiach's message of love and brotherhood and those who reject and rebel against it. There will be no place for any middle ground. This is the result of the so-called Sword of Cleavage.
Note that the consequences above are the natural result of the Christ's presence in the world. They are a result of the energy of Love that emanates from Him - not actually caused by some specific act of will or power on His part.
The initial television appearances in the U.S. have been followed by TV interviews in Mexico, Brazil and Russia. Soon there will be appearances in Japan, Europe and elsewhere. Within a year or at most two years, Moshiach/Maitreya will be well known and accepted by a majority of the people of the world. Soon after that the Moshiach ben David will be joined by Moshiach ben Yosef (Jesus).
Update 2/8/2011: An ethereal figure in white riding a white horse through the crowds gathered in Tahrir Square in Cairo, Egypt, has been seen by many and even captured on video : http://www.youtube.com/watch?v=N6h2-kf8Itg . Benjamin Creme confirms that the Rider on the White Horse was Moshiach/Maitreya, the Christ giving a blessing in order to show the immensity of what the Egyptian people are doing, and that he is with them in their struggle for justice and freedom.
Download the video here. Moshiach has assured us that ultimately 'People Power' will triumph over despotic governments or a powerful military-industrial complex
Possible reactions of the world's religions to the Coming of the Christ/Moshiach/Imam Mahdi:
Christianity - Christians will have great difficulty in accepting Moshiach. They are all waiting for the return of Jesus, not some other Son-of-God, even worse, a Muslim. This will make it very difficult for most Christians to accept him as a Messiah. The fact that Jesus will be junior in status to Moshiach will be intolerable to them. However, I have high hopes for the new Pope - he is a very open-minded as well as genuinely spiritual. I am sure he will recognize Moshiach for what he is - a new Avatar for the Age of Aquarius. (The previous Pope, the one who resigned, would have been a disaster. He would have refused to recognize the Christ. In fact, Ratzinger had been made aware of this story many years ago while he was a Cardinal and just ignored it.) However, even if the current Pope acknowledges the authenticity of Moshiach as an Avatar sent by God, many of his bishops will refuse to go along, since it is a Catholic dogma that Jesus is the one and only begotten Son of God. There will be a great schism in the Catholic Church - it will in fact split into two - those who accept Moshiach as the Christ and those who continue to wait for the 'real' Christ.
Islam - It would seem that it should be easy for Muslims to accept the Imam Mahdi since he will come as a Muslim. But that will not be so. Muslims are even more rigid in their beliefs than Christians. They expect the Imam Mahdi to be an Arab and a descendant of Muhammad. Maitreya will not come as an Arab, but as a Pakistani. Some may say that he could be a Sayyid (a distant descendant) and accept him. The real problem will be that the Imam Mahdi will not promote or favor Islam over other religions. In fact he may not even talk very much about religions or may suggest that everyone just follow the one they were born with. This will not be tolerated by most Muslims - so again there will a major schism - those who accept the Imam Mahdi and those Muslims who do not.
Judaism - The fact that Maitreya will come as a Muslim will be even more difficult for Jews than for Christians. Many of them will reject the Messiah a second time around. Secular or liberal Jews may be the only ones to accept him.
Hinduism - Hindus will have great difficulty accepting a Muslim as an Avatar. But they have been through this before. Shirdi Sai Baba appeared in India as a Muslim in the nineteenth century. Eventually he was accepted by millions of Hindus as an Avatar (although most of them waited till he had died). Hopefully they will not wait that long this time. However, there will still be a large number of Hindus who refuse to accept a Muslim Avatar.
Buddhism - They will have the same difficulty as Hindus. However, if the Dalai Lama accepts him as a Bodhisattva, the acceptance by all Buddhists should be fairly rapid.
Bahais, Ahmadis - The problem for these two groups is that they believe that the Moshiach/Imam Mahdi has already come and gone. That he was the leader of their own sects. I don't really understand why these two groups believe that their respective leaders who have had a relatively small impact on the world, is the Avatar of the Age. It will take some time for these groups to accept that the basis of their religious beliefs needs to be changed so radically.
Atheists/Skeptics - The coming of the Avatar will be a devastating blow to these people. They are as invested in their non-belief as any fundamentalist Christian or Muslim is in his belief. The fact that someone is intellectually superior to themselves or their species is anathema to them. They will not give up their beliefs (or non-belief) easily. They will claim that it is all a trick and a lie. They will say that the voice of Maitreya they heard in their heads was merely some kind of illusion or even a high frequency electronic signal. They will claim that all believers who heard it were subject to mass hysteria and all the miraculous healings were just a placebo effect. Some of them may literally go crazy because of this severe blow to their belief system.
Timeline of Moshiach's Emergence:
1945 - Immediately after the end of WWII, Moshiach announced that he would himself come to the world instead of through a disciple as he had done previously
1971 - He starting creating a body for use while in the world. This body looks human but is practically indestructible and can appear/disappear at will.
July 7, 1977 - Moshiach descended from the Himalayas into the plains of Pakistan
July 19, 1977 - Moshiach arrived and took up residence in London using a Pakistani passport.
Early 1986 - Moshiach met with officials at the BBC at the highest level multiple times. Jesus was present at one of the meetings. Moshiach convinced them of his authenticity by showing them various visions. The BBC decided to take the case to the Queen (as Head of the Church) who conferred with her priests (including the Archbishop of Canterbury). The bishops decided that this was not the real Christ or Jesus and so the story was buried by the BBC and documents were never revealed.
Early 1987 - Moshiach had an interview with a crew at CNN (in this he did not claim to be Moshiach or the Christ). The interview was not broadcast in the US.
11 June 1988 - Moshiach appeared suddenly before 6,000 people at a prayer meeting in Nairobi, Kenya. He gave a talk and then disappeared. Photos were taken and several articles appeared in the local newspapers.
21 and 22 April 1990 - An international conference was held at which Moshiach presided. Some 200 dignitaries were able to accept Maitreya’s invitation over two days. Among the guests were an Ambassador and other diplomats; members of Parliament; religious representatives, including a Bishop and a representative from the Vatican who had already met Maitreya and was totally convinced He was the Christ; a King and other lesser royals; professors; scientists; industrialists; and about 40 journalists. During this time, a documentary film was made in which Maitreya talked about His plans and teachings, His mission and hopes for the world. It was accepted for showing on a major television network in the United States, but was never broadcast.
Beginning in September 1991, Maitreya began appearing miraculously to fundamentalist gatherings of approximately 500–900 people throughout the world. He typically spoke to the group in their own language, outlining His plans and concerns and asking for their help and co-operation. In some cases, photos of Maitreya are taken. In each case, the vast majority of those in attendance believe they have seen the Christ (or for Hindus, Krishna, and for Muslims, the Imam Mahdi). Maitreya has appeared in Mexico, Russia, Germany, Switzerland, Austria, the Middle East, North Africa, India, Pakistan, former Czechoslovakia, Serbia, Scotland, Romania, Norway and Italy, as well as the United States
On 14 January 2010 Benjamin Creme announced that Maitreya had given His first interview, on American television
Maitreya has since given a series of television interviews in the USA, Mexico, Brazil, Russia, China, Japan, Indonesia, Vietnam, Malaysia and India
On 6 July 2016 and on 21 July 2016 at approximately 11.45am (UK time) a special blessing was given to the people of England; it lasted between 15 and 30 minutes in each case. This was a sort of practice run for the Day of Declaration when Moshiach will over-shadow all of humanity
Note: It has taken the Christ so long to emerge because he has to be careful not to infringe on human free will by revealing himself before humanity is ready to receive him.