1) Let's allow the Bible to speak for itself, ok? The Bible is explicitly clear about when Jesus was speaking in parables. Over and over many times in Matthew 13 alone it is careful to tell us when he was giving a parable, but it doesn't do so in Luke 16. If you choose to believe the rich man and Lazarus was a parable, you do so, not because Luke 16 says so, but for your own theological reasons. Jesus said "There was a certain rich man," (Luke 16:19) so I have to believe the man existed or Jesus was wrong. He was no more speaking in parables in verse 19 then he was just one verse earlier in verse 18. Surely you don't think what Jesus said here about adultery was a parable, do you?
2) Names are never mentioned in the parables of Jesus. This is one consistent characteristic of his parables. Rather it be the ten virgins, the sower, the mustard see, the Good Samaritan, or any of the others, no names are mentioned in such parables. If a character is fictitious, its not necessary to give him a name, is it? But in Luke 16 names are mentioned: Abraham and Lazarus, real people. Abraham for sure, the Jews knew.
3) Jesus parables are true to life, meaning, they are based on reality, on things that actually happen. Jesus used things his disciples were familiar with to coin his parables. So he spoke about the shepherd who leaves 99 sheep to look for the lost one because there were shepherds in Israel who knew about this; he spoke about a Good Samaritan because Samaritans were real, and some did have faith like the woman at the well in John 4; he spoke about fishing because many of his disciples were fishermen. All his parables about marriage feasts, leaven fermenting flour and so forth were based on everyday things in Jewish custom. So even if the rich man and Lazarus were a parable, it still was based on something real. Take for example the Good Samaritan:
There really was a road from Jerusalem to Jericho, and that that road really was frequented by robbers. It is a historical fact, you can check this out, that the Romans built a garrison on that road to protect travelers from bandits. Jews were real, so were Samaritans, even the currency, the dinarius was real. So Jesus was no myth maker. He didn't preach fables like Alice in Wonderland. He spoke about real people and places and things. So even if Luke 16:19-31 is a parable, it is still based on something real, therefore, hell is a real place, the fire is real, and these were two real people.
The Greek word for parable is paraboli, and this ame word is translated as "allegory" (KJV) in Galatians 4:24. In this passage (Galatians 4:22-31) we are told that the relationship between Abraham, his two wives, and their sons, as well as the sending away of the one who was slave, was a paraboli, a parable; but no Christian would dare argue that the events mentioned here didn't happen. The Book of Genesis records that Ishmael did persecute Isaac, and Sarah did have her husband send Hagar and her son Ishmael away, and it does record that these were all real people. So parables were based on real life events that used to happen.
4) If hellfire isn't real, then its a false, pagan doctrine. In that case, we are to reach the ridiculous conclusion that Jesus borrowed a false doctrine and used this false doctrine to teach his disciples. Could you imagine Jesus coining an illustration in the Bible that involved mythical gods like Osiris, Anubis, Thor, or Posidon? Could you imagine Jesus putting a false doctrine in the mouth of Abraham, to make him preach about an afterlife and a place of torment that didn't exist? Why would the Son of God have to go to such lengths just to get over a moral point to his disciples?
5) Surely if this were a parable, Jesus would have explained it, or at least the disciples would have asked for an explanation as it was unlike any other parable they had heard before. The parable of the sower is explained by Jesus himself in the Bible, why would he leave us to guess and make assumptions about the meaning of this passage if it was all symbolic?
I can think of other reasons why this is literal, but why do you think it CANNOT be taken literally? Why?
OK, let's assume this is literal and let's examine it...
First point, this was directed at the Pharisees...
Luk 16:14 And the Pharisees also, who were covetous, heard all these things: and they derided him.
so it was definitely a parable...
Mat 13:34 All these things spake Jesus unto the multitude in parables; and without a parable spake he not unto them:
He only spoke directly to His disciples.
Now on to Luke 16...
Luk 16:19 There was a certain rich man, which was clothed in purple and fine linen, and fared sumptuously every day:
Luk 16:20 And there was a certain beggar named Lazarus, which was laid at his gate, full of sores,
Luk 16:21 And desiring to be fed with the crumbs which fell from the rich man's table: moreover the dogs came and licked his sores.
Luk 16:22 And it came to pass, that the beggar died, and was carried by the angels into Abraham's bosom: the rich man also died, and was buried;
Luk 16:23 And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom.
Now they can SEE each other. A far off is a relative term. How far off?
Luk 16:24 And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame.
Luk 16:25 But Abraham said, Son, remember that thou in thy lifetime receivedst thy good things, and likewise Lazarus evil things: but now he is comforted, and thou art tormented.
A far off is still close enough to be able to talk with one another.
Luk 16:26 And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence.
Luk 16:27 Then he said, I pray thee therefore, father, that thou wouldest send him to my father's house:
Luk 16:28 For I have five brethren; that he may testify unto them, lest they also come into this place of torment.
Luk 16:29 Abraham saith unto him, They have Moses and the prophets; let them hear them.
They cannot extend help to the rich man. Carefully note, if this parable is direct teaching, then we are instructed to consult Moses and the Prophets. Are you doing that? Are you living by the Laws of Moses?
Luk 16:30 And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent.
Luk 16:31 And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
If you won't hear Moses and the Prophets, then you won't hear the One who rose from the dead.
Now lets look at a couple of issues here, we discovered in vs 23 that they can see each other. In vs 24-25 they can hear each other and speak to each other but in vs 26 we see they cannot interact. Those in Abraham's bosom cannot extend help to those in hades. OK then, here are some points to consider...
If this is not a parable but rather direct teaching then...
1) Saved mothers in heaven can see their lost children in hell being burned and tormented.
2) Saved mothers in heaven can hear their lost children in hell shrieking and screaming in the fire.
3) Saved mothers in heaven are restricted from helping their children in hell suffering horribly.
So this is your idea of the way a loving God deals with His children for ALL ETERNITY?
It is a parable and not teaching on the subject of heaven and hell.
Here is a good explanation of this parable...
The Real Meaning of The Rich Man and Lazarus by Dr. Ernest Martin