It is the basis of Buddha's teachings to critically examine the teachings and make one's own conclusion. For me I find the the definitive answers in the prayers of Dorje Shugden.
I quote HE Geshe Kelsang Gyatso.
"The confusion arises as the function of Dorje Shugden as a Dharmapala, or 'Dharma Protector', is to protect the Gelug lineage, and especially the Ganden Oral Lineage. According to anti-Shugden proponents who believe the words of the Dalai Lama, the practice of Dorje Shugden includes a promise not even to touch a Nyingma scripture and that he will kill those who violate this vow. Dorje Shugden practitioners cannot find one mention of these words in the collected praises to him. On the contrary Dorje Shugden's function is to protect all living beings from their own delusions and can never harm any living being – as it says in the extensive fulfilling and restoring ritual of the Dharma Protector, the great king Dorje Shugden, in conjunction with Mahakala, Kalarupa, Kalindewi and other Dharma Protectors:
Even though you display the manner of a fearsome being
Amidst a mass of turbulent, blazing fire,
You never move even slightly from the peaceful state of love and compassion.
– Extensive Prayers to Dorje Shugden
and
You said "I will protect as a wealth of merit for all beings
The sublime, stainless essence of the Buddhas' teachings."
– Extensive Prayers to Dorje Shugden
Geshe Kelsang Gyatso claims that Dorje Shugden is an enlightened being who could never harm any living being: "Some people believe that if Gelugpa practitioners practice Nyingma teachings, Dorje Shugden will harm them, but this is completely wrong. We never believe this. Impossible." He adds:
HH the Dalai Lama says: "That cult is actually destroying the freedom of religious thought. Say I want to practise Nyingma. They say this Protector will harm me." This is also completely untrue. We would like to ask HH the Dalai Lama: who are these Shugden practitioners saying these meaningless things? His words are causing disharmony between Shugden practitioners and Nyingma practitioners. Why is HH the Dalai Lama creating this new problem? Until now there have been no problems between Gelugpas and Nyingmapas, and there has been no arguing or criticism. Some scholars debate with each other, such as the well-known Gelugpa scholar Yonten Gyatso and Dongthog Tulku, a scholar from another tradition, who conducted a debate by letter over a number of years. They have written many books replying to each other’s assertions, but this does not mean they are criticising each other. They are simply clarifying the doctrines of their own traditions, with good motivation. There is nothing wrong with this.
I would like to ask: what is the problem between the Nyingma and Gelug traditions? There is none. The majority of people from both traditions naturally live in harmony, so why is HH the Dalai Lama destroying this harmony by saying things like "Shugdens say you should not even touch a Nyingma document"? Although we concentrate on our own tradition we respect all other Buddhist traditions, including the Nyingma, and we rejoice very much in their sincere practice.
"Conservative" Gelugpas may find such language congenial to their views, while "liberals" are more likely to stress the arbitrary nature of such sectarian divisions. Dorje Shugden practitioners have never been considered sectarian. According to Geshe Kelsang Gyatso, the words in the Dorje Shugden prayers are not directed at living beings themselves, nor at other traditions, but at the delusions or negative minds of living beings:
The stainless sun of Je Tsongkhapa’s tradition
Shines throughout the sky of samsara and nirvana,
Eliminating the darkness of inferior and wrong paths;
Please cause its light to spread and bring good fortune to all living beings.
– Brief Prayers to Dorje Shugden
In this context, ‘paths’ do not mean external paths that lead from one place to another. We do not need to study external paths as we can see them directly with our eyes. ‘Paths’ here refer to internal paths, which are by nature our actions. Actions of body, speech and mind that are motivated by ignorance are wrong paths because they lead to suffering, and actions that are motivated by wisdom are correct paths—or spiritual paths—because they lead to happiness.
Because there are different levels of happiness, such as the happiness of liberation and enlightenment, there are different levels of spiritual paths, such as the path to liberation and the path to enlightenment... Moreover, because there are different levels of suffering, such as the sufferings of humans, animals, and hell beings, there are different levels of wrong paths, such as those that lead to rebirth as a human being, animal or hell being. By studying the different types of paths presented by Buddha we can distinguish between correct and incorrect paths, and thereby avoid incorrect paths.
—Geshe Kelsang Gyatso"