According to Catholicism, do the saints and martyrs in heaven rise again on judgment day?

According to Catholicism, do the saints and martyrs in heaven rise again on judgment day?

The answer is Yes, the saints and martyrs glorified souls will be reunited with their resurrected bodies like a "spiritual body".

How do the dead rise?

997 What is "rising"? In death, the separation of the soul from the body, the human body decays and the soul goes to meet God, while awaiting its reunion with its glorified body. God, in his almighty power, will definitively grant incorruptible life to our bodies by reuniting them with our souls, through the power of Jesus' Resurrection.

998 Who will rise? All the dead will rise, "those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of judgment."552

999 How? Christ is raised with his own body: "See my hands and my feet, that it is I myself";553 but he did not return to an earthly life. So, in him, "all of them will rise again with their own bodies which they now bear," but Christ "will change our lowly body to be like his glorious body," into a "spiritual body":554

But someone will ask, "How are the dead raised? With what kind of body do they come?" You foolish man! What you sow does not come to life unless it dies. And what you sow is not the body which is to be, but a bare kernel. . . . What is sown is perishable, what is raised is imperishable. . . . The dead will be raised imperishable. . . . For this perishable nature must put on the imperishable, and this mortal nature must put on immortality.555

555 1 Cor 15:35-37,42,52,53

Do Saints and martyrs who are already in heaven rise again on judgment day and assume a new body?

There are things to consider regarding this question, what body will rise again.

1. Jesus was raised in His own body because it was not subject to corruption.
2. The bodies of the saints and martyrs whose bodies are incorruptible.
3. The bodies of the baptized believers who suffered decays and return to dust.

In the case of Jesus, He was resurrected with His own body having it's visible wounds retain.

"Then He said to Thomas, "Reach here with your finger, and see My hands; and reach here your hand and put it into My side; and do not be unbelieving, but believing."(John20:27)

How about the Blessed Virgin Mary, Her sinless body was assumed into Heaven because like Jesus it was not subject to corruption because of Church belief on the Dogma of Immaculate Conception and Dogma of Mary's Assumption.

How about the "incorruptible bodies" of the Saints & Martyrs?

Like Jesus and Mary, there was also the pious tradition that St.Joseph sinless body was also assumed into Heaven. Will the incorruptible bodies of the Saints & Martyrs like St.Padre Pio, St.Bernadette Soubirous, St.Catherine of Laboure to name a few be also assumed into Heaven?

The Catholic Church teaches that the "glorified souls" of the Saints & Martyrs who are in Heaven will be reunited with their resurrected bodies at the last day.

999 How? Christ is raised with his own body: "See my hands and my feet, that it is I myself";553 but he did not return to an earthly life. So, in him, "all of them will rise again with their own bodies which they now bear," but Christ "will change our lowly body to be like his glorious body," into a "spiritual body":554

How about the bodies of the baptized believers who make it to Heaven by way of purification and whose bodies suffered decays and return to dust?

997 What is "rising"? In death, the separation of the soul from the body, the human body decays and the soul goes to meet God, while awaiting its reunion with its glorified body. God, in his almighty power, will definitively grant incorruptible life to our bodies by reuniting them with our souls, through the power of Jesus' Resurrection.

If so, why when they are already in heaven and with the Lord?

All of us upon death will face a particular judgment according the the teaching of the Catholic Church. The souls of the Saints & Martyrs since they merit a crown in Heaven by their pious life here on earth wiil be glorified in Heaven. While, the souls who had not perfected their virtues will go to Purgatory first to purge their imperfection. While the souls, who rejected the Mercy of God upon death will go to Hell.

998 Who will rise? All the dead will rise, "those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of judgment."552

Remember also your Creator in the days of your youth, . . . before the dust returns to the earth as it was, and the spirit returns to God who gave it.(Eccl 12:1,7)

1013 Death is the end of man's earthly pilgrimage, of the time of grace and mercy which God offers him so as to work out his earthly life in keeping with the divine plan, and to decide his ultimate destiny. When "the single course of our earthly life" is completed,586 we shall not return to other earthly lives: "It is appointed for men to die once."587 There is no "reincarnation" after death.

As mentioned by the other two answers, this is one of those things that is very clearly taught in the Bible and therefore the Vatican does not teach against it; indeed at most masses the parishioners will recite either the Nicene Creed or the Apostles' creed, the latter speaking of "I believe in [...] the resurrection of the body," and the former speaking of "We look for the resurrection of the dead, and the life of the world to come."

One might even say that Paul gets giddy about it when he speaks about it in 1 Cor 15:

³⁵ But someone will ask, "How are the dead raised? With what kind of body do they come?" ³⁶ Fool! What you sow does not come to life unless it dies. ³⁷ And as for what you sow, you do not sow the body that is to be, but a bare seed, perhaps of wheat or of some other grain. ³⁸ But God gives it a body as he has chosen, and to each kind of seed its own body. ³⁹ Not all flesh is alike, but there is one flesh for human beings, another for animals, another for birds, and another for fish. ⁴⁰ There are both heavenly bodies and earthly bodies, but the glory of the heavenly is one thing, and that of the earthly is another. ⁴¹ There is one glory of the sun, and another glory of the moon, and another glory of the stars; indeed, star differs from star in glory. ⁴² So it is with the resurrection of the dead. What is sown is perishable, what is raised is imperishable. ⁴³ It is sown in dishonor, it is raised in glory. It is sown in weakness, it is raised in power. ⁴⁴ It is sown a physical body, it is raised a spiritual body. If there is a physical body, there is also a spiritual body. ⁴⁵ Thus it is written, "The first man, Adam, became a living being"; the last Adam became a life-giving spirit. ⁴⁶ But it is not the spiritual that is first, but the physical, and then the spiritual. ⁴⁷ The first man was from the earth, a man of dust; the second man is from heaven. ⁴⁸ As was the man of dust, so are those who are of the dust; and as is the man of heaven, so are those who are of heaven. ⁴⁹ Just as we have borne the image of the man of dust, we will also bear the image of the man of heaven. ⁵⁰ What I am saying, brothers and sisters, is this: flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. ⁵¹ Listen, I will tell you a mystery! We will not all die, but we will all be changed, ⁵² in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised imperishable, and we will be changed.

In other words, we're going to have bodies, but they're not going to be these smelly deathy fleshy bodies that we have, but shiny new bodies made of new matter for a new purpose, which are not subject to death: they did not come from dust therefore it is not the case that "to dust you shall return". And the whole process will seem rather like planting a seed (our physical body) on the Earth, from which a tree (our resurrection bodies) will spring, looking nothing particularly like the original seed.

Right now they exist purely as souls or spirits up in heaven, but the point is that they are coming back here at the last trumpet, and when they do, it is not by them coming to life as zombies.

1 Thessalonians 4 says,

13 Brothers and sisters, we do not want you to be uninformed about those who sleep in death, so that you do not grieve like the rest of mankind, who have no hope. 14 For we believe that Jesus died and rose again, and so we believe that God will bring with Jesus those who have fallen asleep in him. 15 According to the Lord’s word, we tell you that we who are still alive, who are left until the coming of the Lord, will certainly not precede those who have fallen asleep. 16 For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. 17 After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever. 18 Therefore encourage one another with these words.

This scripture is much debated by Christians. Some (such as premillennial dispensationalists) claim it refers to a rapture of the faithful that occurs prior to the final judgment, while others claim that it refers to the final return of Christ and is immediately followed by the judgment.

The Catholic Church does not teach (and in fact teaches against) the rapture view. It does teach that some souls may spend time in Purgatory (if purification from past sins is necessary) en route to Heaven, while others do not need such purification because their trials on Earth already accomplished their cleansing. Given that the souls of the departed may reside in different places and have different forms, Thessalonians describes the reunion of Christ and all his church, those living, dead, in Purgatory or not and their assumption of their final glorified form.

These scriptures describe the event but do not explain why.

Yes according to the Catholic Church the bodies of the saints and martyrs in heaven rise again on judgment day.

St Thomas Aquinas states in his Summa Theologica:

The saints in heaven, since they are blessed, have no lack of bliss, save that of the body's glory, and for this they pray. But they pray for us who lack the ultimate perfection of bliss: and their prayers are efficacious in impetrating through their previous merits and through God's acceptance.

The Catholic Church teaches that the only saint to be in heaven in both body and soul is the Blessed Virgin Mary.

This doctrine was dogmatically defined by Pope Pius XII on 1 November 1950, in the apostolic constitution Munificentissimus Deus by exercising papal infallibility.