Being born again:
Yahchanan 3:4-6, "Nicodemus said to Him; How can a man be reborn when he is old? Can he enter the womb of his mother the second time, and be born? Yahshua answered: Truly, truly, I say to you: Unless a man is begotten of water and the Spirit, he cannot enter into the Kingdom of Yahweh. That which is born of the flesh, is flesh; but that which is born of the Spirit, is spirit."
1 Corinthians 15:19-54, "And just as we have borne the image of the earthy, so will we also bear the image of the heavenly. Now I say this brothers: that flesh and blood cannot inherit the Kingdom of Yahweh; neither does corruption inherit incorruption. The First Resurrection At The Last Trumpet Behold, I show you a secret truth: we will not all sleep, but we will all be changed--In a moment, in the twinkling of an eye, at the clast trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we will be changed. For this corruptible must put on incorruption, and this mortal must put on immortality. So when this corruptible will have put on incorruption, and this mortal will have put on immortality, then will be brought to pass the saying that is written: Death is swallowed up in victory."
The "pre-tribulation reapture" was never preached before around 1830, it was invented to trick people into following the anti-Messiah when he arrives, people will be tole that "meeting Christ in the air" is not literal, it is a higher state of consciousness, and the kingdom is here now, when it will actually be satans kingdom.
"Once saved always saved":
Romans 3:25, "Whom Yahweh set forth as a sacrifice of atonement by His own blood, through the faith, to declare His righteousness for the remission of sins that are past, through the forbearance of Yahweh."
Hebrews 10:26-27, "For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, But a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries."
No one is actually saved untill they enter the kingdom of Yahweh.
Mattithyah 10:22, "And you will be hated above all men for My Name's sake; but he who endures to the end will be saved."
Mattithyah 24:12-13, "And because iniquity; (the breaking of Yahweh's Law), will abound, the love of the many will grow cold. But he who endures until the end, the same will be saved.."