According to the wiki page this album is the Devil’s gift to Death metal. The band was formed back in 1983, had a debut in 1986, and then came with this in 1989. The debut was not to the band leader Trey Azagthoth’s liking though, and was only released in very small numbers. Altars however was a huge success, and caught the attention of fellow metal bands that wanted to emulate the style. It formed the bridge between thrash metal (the likes of early Metallica) and what became death metal.
Thematically what Morbid Angel did was not that far remote from where aforementioned Metallica was. They too were fascinated with the dead gods of ancient civilisations like Sumeria and the Romans. They too had some Lovecraft on the side. When I first heard bands like this (the likes of Obituary and Deicide) I was totally into it. I might not have understood all the lyrics (there is a lot of grunting involved), but I really liked the dark atmosphere. It was the birth of Gothic me.