Maitreya Buddha is who many Buddhists are looking for to come to earth to renew Buddhist teaching and bring enlightenment on the earth. It's about supposed enlightenment attained through successive reincarnations until release from the wheel of rebirth. The western Theosophical Society groups of the 1900's used teachings about Maitreya to propose the idea of hidden masters living on an astral heavenly plane outside human existence, and as benefactors and directors of spiritual enlightenment to the world. In that they heavily associated Maitreya with our Lord Jesus, and heads of the main founded religions on earth, like the idea of avatars coming to earth every so many thousands of years to move man forward to the path of enlightenment.
The Truth?
There is no other Name under Heaven given man that we may be saved by other than the Name Jesus Christ (Acts 4:10-12).
In old times God did not reveal Himself to other nations as He did with Israel. But He obviously planted the idea of His Existence in the hearts of minds within those other nations early on (like Paul says in Romans 1). But by confusion they instead began worshiping the things of His creation because of not knowing Him. God foretold His coming Salvation through His Old Testament prophets, declaring The Christ would be sent, and HOW He would come. Christ came, was rejected by many of Israel, crucified on a tree, and was raised by The Father on the third day, as witnessed by those who were with Him that saw Him thereafter. And then He sent His servants to preach The Gospel Salvation Message to all... nations.
The Gospel of Jesus Christ has gone out to all nations today. Those like the western Theosophists, Gnostics, and mystical fraternities of initiation claim Jesus of Nazareth was only an avatar, like Buddha, Zoroaster, Krishna, Confucius, etc., and had only attained... The Christ Spirit as they also had.
Thus, they teach separation between the idea of The Christ as Spirit, and Jesus as a flesh man only, and not Jesus as Christ-God The Son (which The Bible does teach). This is because of their idea that we each can 'attain' enlightenment and become our own Christ, which is actually the falsehood that we can be our own God (the temptation Satan as the serpent played upon Eve in God's Garden).
Today, those same western and eastern factions are joining together because of their independent religious beliefs have similarities that point out they all may be expecting the same Holy One soon to appear on earth, their main differences between them being different languages, customs, and religious traditions that point to an expected Messiah. In this they are attempting to band all the world's religions together in prep for the one they look for. They include many among Judaism and Christianity within that one-world religious joining.
The Truth?
The Word of God warns His people that a false messiah is coming to earth first, and that he will exalt himself over all that is worshiped, and do miracles, great wonders, and signs on the earth, and, that the majority of the world will worship him as God. And then The True Christ will return to destroy that fake one who comes first.