Namaste
Obviously, as a Hindu, I spend my "God as form" activities with Hindu Devatas, and am in good relations with many of them. In my path, I put a lot of emphasis on Kashi (Varanasi) where "all the Gods have come". The number in my path is 330 million "Gods" (since this is not a Hindu DIR, I am using general terms). Just as there is an advantage of memory capability regarding remembering the names of business partners, friends and relatives, associates, and this ability is a "science" of its own, I hope to one day know all the names and associated "faces" of all 330 million "Gods" but this will not be achieved in this life, it may take many lives (and some names are the same Devata since many have many names, or 108 names or 1008 names, or even nick-names). I am in no particular rush to Moksha, but that may happen anyway.
But in regards to Jesus, Mahavira and Buddha, I have no problem with them at all. Especially Mahavira, I am a huge admirer, and as my Mother loved Buddha so I like Siddhartha a lot who was born a Hindu actually.
Jesus, why would I hate? I do not. What a wonder if Jesus would speak in person here in California, I would definetly drive to L.A. to hear, not trying to sound smarty pants, I am serious. But I do not know much about Christianity, like I know for example Jainism and (Indian) Buddhism.
As far as avatars, Shiva does not have avatars (incarnations), but rather has manifestations and emanations. I don't want to get "technical", but Vishnu has incarnations, not Shiva or Brahma, nor Devi.
Jesus was not an incarnation. Mahavira was a self-realized arhant. Buddha was a self-realized Hindu reformer and influenced by Jainism. Krishna was an incarnation, but also a Hindu reformer regarding rituals to Vedic Gods. So that is my "skull bearer" Saiva perspective.
Om Namah Sivaya