who are "those" and what is the cause for them to "go immediately to heaven"?
Pilgrim has answered these type of question in - Pilgrim in post 75 says:
I wouldn't know because I can't prove it. But neither can you disprove it. I look to the lives of the saints. Many of them had extraordinary gifts given to them by God: gifts of bilocation, prophecy, visions, reading hearts,etc. I believe that most if not all reached perfection in their lives.
Matt 9:24
Jesus answered, “If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me.”
Post 109
Those who when they die go immediately to heaven.
Pilgrim offers no proof for these assumptions.
But a lot of these saints like to do self mortification which is not found in scripture:
saint John of the Cross: "The ignorance of some is extremely lamentable; they burden themselves with extraordinary penances and many other exercises, thinking these are sufficient to attain union with divine Wisdom. But such practices are insufficient if these souls do not diligently strive to deny their appetites. If they would attempt to devote only half of that energy to the renunciation of their desires, they would profit more in a month, than in years with all these other exercises... I venture to say that without this mortification, all that is done for the sake of advancement in perfection and in knowledge of God and of oneself is no more profitable than seed sown on uncultivated ground (that is, only producing weeds). Accordingly, darkness and coarseness will always be with a soul until its appetites are extinguished."
Saint Teresa of the Andes: I don't know what to do to get the priest to allow me to mortify myself. I have so many desires to fast, to wear hair shirts, since I see it is necessary for me to mortify not only my will, but also my body. My Jesus, give me permission to do penance. My Mother, inspire the priest to grant me permission."
Diary, Saint Faustina: "Interior mortifications take the first place, but besides this, we must practice exterior mortifications, strictly determined, so that all can practice them. These are: on three days a week, Wednesday, Friday and Saturday, there will be a strict fast. Each Friday, all the sisters – each one in her own cell – will take the discipline for the length of the recitation of Psalm 50 and all will do this at the same time; namely, three o’clock; and this will be offered for dying sinners. During the two great fasts, ember days and vigils, the food will consist of a piece of bread and some water, once a day."
Saint Alphonsus De Ligouri: "If we read the lives of the saints and see the works of penance that they performed, we shall be ashamed of the delicacy and of the reserve with which we chastise the flesh... Our pilgrimage on earth will not be of long duration: our home is eternity, where he who has practiced the greatest mortifications during life shall enjoy the greatest glory."
From Penance & Mortification, religious vocation
Other examples of this type of behaviour are listed in post 85.
Where in scripture does it say that flagellation and mortification etc are necessary to be perfect?