Did Lot's wife go to heaven or hell for her sin of looking back?
"When the morning dawned, the angels urged Lot to hurry, saying, "Arise, take your wife and your two daughters who are here, lest you be consumed in the punishment of the city." And while he lingered, the men took hold of his hand, his wife's hand, and the hands of his two daughters, the LORD being merciful to him, and they brought him out and set him outside the city. So it came to pass, when they had brought them outside, that he said, "Escape for your life! Do not look behind you nor stay anywhere in the plain. Escape to the mountains, lest you be destroyed." ... Then the LORD rained brimstone and fire on Sodom and Gomorrah, from the LORD out of the heavens. So He overthrew those cities, all the plain, all the inhabitants of the cities, and what grew on the ground. But his wife looked back behind him, and she became a pillar of salt" (Genesis 19:15-17, 24-26).
The question basically is, "Was Lot's wife's violation of a direct command from an angel of God enough to keep her out of heaven?" We are not directly told concerning the final fate of most people mentioned in the Bible. However, for many it is not hard to guess. Somehow, we dislike the thought that one sin by a person could have such great eternal consequences.
In discussing the future destruction of Jerusalem, Jesus gave this warning: "And as it was in the days of Noah, so it will be also in the days of the Son of Man: They ate, they drank, they married wives, they were given in marriage, until the day that Noah entered the ark, and the flood came and destroyed them all. Likewise as it was also in the days of Lot: They ate, they drank, they bought, they sold, they planted, they built; but on the day that Lot went out of Sodom it rained fire and brimstone from heaven and destroyed them all. Even so will it be in the day when the Son of Man is revealed. In that day, he who is on the housetop, and his goods are in the house, let him not come down to take them away. And likewise the one who is in the field, let him not turn back. Remember Lot's wife. Whoever seeks to save his life will lose it, and whoever loses his life will preserve it" (Luke 17:26-33). Many people lost their lives in the fall of Jerusalem because they would not heed the warnings given. They continued their sinful lives as if nothing would ever happen. Noah spent 120 warning the world that a flood was coming and only his own immediate family listened (II Peter 2:5). Lot warned his daughters and son-in-laws, but they would not listen. They were destroyed in the fall of Sodom (II Peter 2:6).
But what about Lot's wife? She left the city. Her only fault was looking back. But that longing for what was left behind serves as a warning. When Jerusalem fell, Jesus warned it would fall suddenly. There wouldn't even be time to grab things to take with you. In order to live, the people escaping had to leave with no hesitation, no desire for what they left behind. Lot's wife serves as a warning.
Her death serves as a warning to us as well. Jesus stated, "No one, having put his hand to the plow, and looking back, is fit for the kingdom of God" (Luke 9:62). Yet many try to become Christians while keeping one foot in their past lives. It doesn't work! "Therefore, since Christ suffered for us in the flesh, arm yourselves also with the same mind, for he who has suffered in the flesh has ceased from sin, that he no longer should live the rest of his time in the flesh for the lusts of men, but for the will of God. For we have spent enough of our past lifetime in doing the will of the Gentiles--when we walked in lewdness, lusts, drunkenness, revelries, drinking parties, and abominable idolatries" (I Peter 4:1-3). You can't leave sin by looking over your shoulder missing what you left behind.
Lot's wife also warns us that God means what He said. "For if the word spoken through angels proved steadfast, and every transgression and disobedience received a just reward, how shall we escape if we neglect so great a salvation, which at the first began to be spoken by the Lord, and was confirmed to us by those who heard Him" (Hebrews 2:3-4).
We are not told what Lot's wife's eternal destiny will be, but given the fact that God saw her sin as great enough to deserve a death sentence, it is likely that sentence was permanent. Too many talk about the goodness and love of God, but they willingly forget that God is also just. "And do you think this, O man, you who judge those practicing such things, and doing the same, that you will escape the judgment of God? Or do you despise the riches of His goodness, forbearance, and longsuffering, not knowing that the goodness of God leads you to repentance? But in accordance with your hardness and your impenitent heart you are treasuring up for yourself wrath in the day of wrath and revelation of the righteous judgment of God, who "will render to each one according to his deeds": eternal life to those who by patient continuance in doing good seek for glory, honor, and immortality; but to those who are self-seeking and do not obey the truth, but obey unrighteousness -- indignation and wrath, tribulation and anguish, on every soul of man who does evil, of the Jew first and also of the Greek; but glory, honor, and peace to everyone who works what is good, to the Jew first and also to the Greek. For there is no partiality with God" (Romans 2:3-11).
Isn't it odd that so many willfully sin, without a worry in the world, because they are certain that God will forgive them of anything they might do wrong. Instead, we could all do with a large dose of fear. "Therefore, since a promise remains of entering His rest, let us fear lest any of you seem to have come short of it" (Hebrews 4:1). What happened to Lot's wife ought to scare you.