Skilful actions that lead to good karmic outcomes are based upon motives of generosity; compassion, kindness and sympathy, and clear mindfulness or wisdom. The opposite motives of greed, aversion (hatred) and delusion, when acted upon, lead to bad karmic results.
Saying something negative and hurtful can create bad karma.
Karma is deeply connected with the things you say to others. Saying something with harsh, cruel, and negative intentions creates negative karma, no matter who you're talking to.
The Vajrasatva mantra has been used for centuries in the Tibetan Buddhist tradition to purify negative karma. We can think of the negative actions we have commited, and with a sense of regret, use the mantra and visualisation to purify ourselves.
If you have bad karma that you were born with or have accumulated over the course of your life, then you can't just replace it with good karma. No amount of “good” actions will remove negative karma from your destiny.
Evil actions, like killing, stealing, lying and so on, are bad karmas and will lead to rebirth in an unpleasant human situation or in hell. Good actions, on the other hand, such as generosity (especially giving to Buddhist monks), makes merit and leads to good rebirth in a pleasant human situation or in heaven.
The Dhammasangāni [5] regard five acts – matricide, parricide, slaying an Arhat, slaying a Buddha, and causing division among priesthood to be five unpardonable sins.
Pride (superbia), also known as hubris (from Ancient Greek ὕβρις) or futility. It is considered the original and worst of the seven deadly sins on almost every list, the most demonic. It is also thought to be the source of the other capital sins. Pride is the opposite of humility.
Good deeds create positive karma, and bad ones create negative karma. Positive karma will lead to good fortune and a blessed life; negative karma will lead to misfortune and suffering.
Hence, karma always hits you back, but how badly it hits you depends upon the karmic intensity of that karma which is coming back. Each act of your freewill i.e. the kriyamana/agama karma (Vartamana) which is the “current living”, adds to your eventual fate. Karmic intensities applies to every realm of our existence.
Therefore I tell you, people will be forgiven for every sin and blasphemy, but blasphemy against the Spirit will not be forgiven. Whoever speaks a word against the Son of Man will be forgiven, but whoever speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come."
Lust, envy, anger, greed, gluttony and sloth are all bad, the sages say, but pride is the deadliest of all, the root of all evil, and the beginning of sin.
The strongest of the Seven Deadly Sins is Escanor, the Lion's sin of Pride.
The basic causes of suffering are known as the Three Poisons : greed, ignorance and hatred. These are often represented as a rooster (greed), a pig (ignorance) and a snake (hatred).
In his early teachings, the Buddha identified “three poisons,” or three fires, or three negative qualities of the mind that cause most of our problems—and most of the problems in the world. The three poisons are: greed (raga, also translated as lust), hatred (dvesha, or anger), and delusion (moha, or ignorance).
They are the three physical evils of killing, stealing, and sexual misconduct; the four verbal evils of lying, flattery or indiscriminate and irresponsible speech, defamation, and duplicity; and the three mental evils of greed, anger, and foolishness or the holding of mistaken views.
The five actions that are so heavy that they cause one to be reborn in hell immediately after death. They are: 1) killing one's mother; 2) killing one's father; 3) killing an arhat; 4) maliciously drawing blood from a buddha; and 5) creating a schism in the Sangha.
Tibetan Buddhism
In the Vajrayana tradition, negative past karma may be "purified" through such practices as meditation on Vajrasattva because they both are the mind's psychological phenomenon.
Although souls alone have the freedom and responsibility for their acts and thus reap the fruits of karma, i.e., good and evil karma, God as Vishnu, is the supreme Enforcer of karma, by acting as the Sanctioner (Anumanta) and the Overseer (Upadrasta).
Good karma is a result of good deeds done for others, while bad karma results from intentional harm caused to others. If your actions cause lasting pain and suffering, they are regarded as negative, unvirtuous, or destructive. If your actions cause happiness, they are considered constructive, positive, and virtuous.
It is also possible to take on someone else's Karma, which generally isn't a good idea, because you have enough of your own. This can happen from stealing another's belongings, gossiping, or fantasizing.
I believe that God can forgive all sins provided the sinner is truly contrite and has repented for his or her offenses. Here's my list of unforgivable sins: ÇMurder, torture and abuse of any human being, but particularly the murder, torture and abuse of children and animals.