Addressing the OP,
not Failed but misunderstood. example,
Matthew 16:27-28:
"For the Son of Man is going to come in his Father's glory with his angels, and then he will reward each person according to what they have done. Truly I tell you, some who are standing here will not taste death before they see the Son of Man coming in his kingdom."
these two verses speak of two different events. One has happened already and the Other one is yet to come.
one must A. KNOW, and B. UNDERSTAND the Lord Jesus two-fold return.
one return in "Spirit", which happen on the day of Pentecost, "
some who are standing here will not taste death before they see the Son of Man coming in his kingdom". this is the return that Judas, not Iscariot, asked about. John 14:19 "Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also." John 14:20 "At that day ye shall know that I am in my Father, and ye in me, and I in you." John 14:21 "He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will
manifest myself to him." John 14:22 "Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world?"
answer, on the day of Pentecost he, the Lord JESUS,
manifested himself in the Spiritual Gifts, which fulfills, "
some who are standing here will not taste death before they see the Son of Man coming in his kingdom".
now, his second Coming in Flesh, ALL THE WORLD WILL SEE HIM THEN. Hebrews 9:28 "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."
this "APPERANCE" all will see, Revelation 1:7 "Behold, he cometh with clouds;
and every eye shall see him, and they also which pierced him: and all kindreds of the earth shall wail because of him. Even so, Amen."
so the Lord Jesus first return, (which was in Spirit), happen on Pentecost, in
MANIFESTATION of the Spiritual Gifts. his SECOND return is in "
APPERANCE", and EVERY EYE WEILL SEE HIM.
so there is a two-fold return of the Lord Jesus.
people KNOW YOUR BIBLE.
101G.