Just as with Star Trek's "Prime Directive", IMO it is far far more likely any visiting intelligent entities (IEs) would not do so openly in a technology era as so many ordinary people tend to expect. And given our human science and technology era is but an infinitesimal small recent period versus an immense geological time of life on this planet, one might expect IEs interested in watching we humans, prepared for being secretive once we developed technology, long long before humans had developed any science and technology. So yeah, they may have a base now in obscure camouflaged places we might never figure out, especially under the ocean.
My own leanings are that what people call "God" is not what they think but rather IEs (and mostly if not all non-organic AIs) despite endless religious authorities claiming otherwise. As in there is no such thing as Magic miracles...actions without forces. Any science logical person analyzing the Bible would quickly come to realize both the OT and NT are NOT inerrant and mostly written by men. And significantly the Bible scripture itself shows the Omniscient, Omnipresent, Omnipotent narratives religions push as dogma and Middle Ages philosophers created, is nonsense.
That noted, this person does expect IEs actually are responsible for passing on information and moral help, some of what is in the Bible and that includes Jesus and the gift of eternal life. But what men later recorded was not fully inspired nor "fixed" if incorrect by IEs, that is actually a rather nonsense idea given scripture.
My own conjecture is that IEs became particularly interested in our relatively remote planet once earlier ape homo species arose, then bred them into homo sapiens just like we breed dogs plus some direct DNA brain enhancement work. And if they do offer eternal life, that is a huge incentive for any humans promised such that they bring into their confidence, to remain quiet while working with them. In fact, IMO the Adam and Eve Genesis narrative probably has some truth in it as a second "release" of superior human DNA that in the end failed to be good enough so they abandoned such. Jesus's DNA could have come from that. Why Adam's and his offspring supposedly lived for hundreds of years. And why there was a supplemental "Tree of Life".
Secret UFO civilization, aliens could be here on Earth already: Harvard scientists 
