It is an interesting topic this one. For me, my understanding of scripture is that death is compared to as a sleep in which all wait until the coming of Christ at which time the dead (those that sleep) will rise from their graves for the judgement. According to the scriptures we are not in heaven as many claim but await for the 2nd coming...
To be dead is to sleep....
John 11:11-13
11, These things said he: and after that he saith unto them, Our friend Lazarus sleeps; but I go, that I may awake him out of sleep. 12, Then said his disciples, Lord, if he sleep, he shall do well. 13, Howbeit Jesus spake of his death: but they thought that he had spoken of taking of rest in sleep. 14, Then said Jesus unto them plainly, Lazarus is dead.
Mark 5:35-39
35, While he yet spake, there came from the ruler of the synagogue's house certain which said, Thy daughter is dead: why troublest thou the Master any further? 36, As soon as Jesus heard the word that was spoken, he saith unto the ruler of the synagogue, Be not afraid, only believe. 37, And he suffered no man to follow him, save Peter, and James, and John the brother of James. 38, And he cometh to the house of the ruler of the synagogue, and seeth the tumult, and them that wept and wailed greatly. 39, And when he was come in, he saith unto them, Why make ye this ado, and weep? the damsel is not dead, but sleeps.
Matthew 27:50-53
50, Jesus, when he had cried again with a loud voice, yielded up the ghost. 51, And, behold, the veil of the temple was rent in twain from the top to the bottom; and the earth did quake, and the rocks rent; 52, And the graves were opened; and many bodies of the saints which slept arose <These saints were in the grave sleeping not heaven as some claim>, 53, And came out of the graves after his resurrection, and went into the holy city, and appeared unto many.
Sleeping with the fathers means to be dead (theses are a few scriptures there are too many to list)....
Act 13:36
For David, after he had served his own generation by the will of God, fell on sleep, and was laid unto his fathers, and saw corruption
Deuteronomy 31:16
And the LORD said unto Moses, Behold, thou shalt sleep with thy fathers; and this people will rise up, and go a whoring after the gods of the strangers of the land, whither they go to be among them, and will forsake me, and break my covenant which I have made with them.
1 Kings 2:10
So David slept with his fathers, and was buried in the city of David.
1 Kings 11:43
And Solomon slept with his fathers, and was buried in the city of David his father: and Rehoboam his son reigned in his stead.
1 Kings 14:20
And the days which Jeroboam reigned were two and twenty years: and he slept with his fathers, and Nadab his son reigned in his stead.
1 Kings 14:31
And Rehoboam slept with his fathers, and was buried with his fathers in the city of David. And his mother's name was Naamah an Ammonitess. And Abijam his son reigned in his stead.
1 Kings 15:8
And Abijam slept with his fathers; and they buried him in the city of David: and Asa his son reigned in his stead.
1 Kings 15:24
And Asa slept with his fathers, and was buried with his fathers in the city of David his father: and Jehoshaphat7 his son reigned in his stead.
1 Kings 16:6
So Baasha slept with his fathers, and was buried in Tirzah: and Elah his son reigned in his stead.
1 Kings 16:28
So Omri slept with his fathers, and was buried in Samaria: and Ahab his son reigned in his stead.
1 Kings 22:40
So Ahab slept with his fathers; and Ahaziah his son reigned in his stead.
1 Kings 22:50
And Jehoshaphat slept with his fathers, and was buried with his fathers in the city of David his father: and Jehoram his son reigned in his stead.
2 Kings 8:24
And Joram slept with his fathers, and was buried with his fathers in the city of David: and Ahaziah his son reigned in his stead.
(many more in the books of Kings, Chronicle and Samuel)
Job 7:21
And why dost thou not pardon my transgression, and take away mine iniquity? for now shall I sleep in the dust; and thou shalt seek me in the morning, but I shall not be
Job 14:12
So man lies down, and rises not: till the heavens be no more, they shall not awake, nor be raised out of their sleep.
Psalms 13:3
Consider and hear me, O LORD my God: lighten mine eyes, lest I sleep the sleep of death;
Ecclesiastes 9:3-6
3, This is an evil among all things that are done under the sun, that there is one event unto all: yea, also the heart of the sons of men is full of evil, and madness is in their heart while they live, and after that they go to the dead. 4, For to him that is joined to all the living there is hope: for a living dog is better than a dead lion. 5, For the living know that they shall die: but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten. 6, Also their love, and their hatred, and their envy, is now perished; neither have they any more a portion for ever in any thing that is done under the sun.
Psalms 115:17
The dead praise not the LORD, neither any that go down into silence.
Jesus sending out the 12 giving them the Holy Spirit to raise the dead.......
Matthew 10:5-8
5, These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: 6, But go rather to the lost sheep of the house of Israel. 7, And as ye go, preach, saying, The kingdom of heaven is at hand. 8, Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.
The dead that sleep are to be risen from the graves and wake from death for the judgement at the second coming. If the dead are already in heaven why would they be raised from the graves at the 2nd coming?
1 Thessalonians 4:13-17
13, But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope. 14, For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. 15, For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. 16, For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first:17, Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
1 Corinthians 15:50-55 (Feast of first fruits Resurrection to eternal life - Jesus v 20)
50, Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption. 51, Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, 52, In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed. 53, For this corruptible must put on incorruption, and this mortal must put on immortality. 54, So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory. 55, O death, where is thy sting? O grave, where is thy victory?
Philippians 3:10-11
10, That I may know him, and the power of his resurrection, and the fellowship of his sufferings, being made conformable unto his death; 11, If by any means I might attain unto the resurrection of the dead.
Daniel 12:2
And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt.
Hope this helps may God bless you as you seek him through His Word!