While Captain America chided, "Language" to the team, he didn't call out "Blasphemy" when the Vision declared, "I am."
But I think Joss Whedon, despite his vocal atheism, must have some working Biblical knowledge. This wouldn't be the first time he's made reference to Christianity or the Bible. Remember the first Avengers movie in which Captain added the line, "There's only one God ... and he doesn't dress like that!" In the same movie, Stark asks his A.I. Jarvis if he remembers the story of Jonah. Jarvis notes that he doesn't think Jonah was a role model.
All good things. Jonah, in fact, is not a role model. The whole going into the belly of the great fish was a result of his sinful will to run from God's direct order to preach repentance to a wicked city that was oppressing Jonah's ethnic people.
In the Age of Ultron, Joss is tackling the issue of human depravity. As Nick Fury notes, "Trouble, there's always trouble." Yep. And, as Ultron sees it, humans are to blame. Evoking the story of Noah and the Ark, Ultron feels it is his mission to destroy humanity to give it a fresh start. Like God and Noah did in the Bible.
One problem: Ultron isn't God or Noah. God is all knowing and the Creator, so He would know what is best. Utron is once removed from the creations of God (in this fictional setting) having been created by a human. The movie implies that Ultron actually inherited the hubris of Tony Stark with none of Stark's mediating compassion. In other words, he hates the bad things of the world, but knows no love.
Without spoiling any plot points, the character of the Vision comes to life at a time where no one can trust anyone else. Since the last robotic A.I. has determined to destroy the world, the Avengers are not so sure about this new one. In answering who he is, he says that he doesn't know, but that "I am."
I think Joss, with his knowledge of the Bible is well aware that God is the great I Am. It's what he told Moses to say when they asked who God was. Those were the words Jesus spoke, which had the Pharisees call for his stoning at one point. Joss knows what those words mean.
It seems to me that Joss is not lost on the idea that the world needs saving. All of comic book hero stories generally involve a world on the brink of destruction, needing saving. We look to heroes, naturally. In Age of Ultron, Stark tries to make a hero to save the world and to take away the burden that the Avengers share.
If you'll indulge me, the Avengers might be like the Apostles, taking the salvation to the world. What Christian doesn't want rest from the burden of the Great Commission? The mistake in the movie would be to create some salvation other than Jesus. With Vision, it seems that Joss is giving him that Messianic quality.
Is it blasphemy? Yes, in the strictest sense. But, it does open a conversation. And Joss is not a believer whose mind has been enlightened by the Holy Spirit of God. So, we might properly say, he knows not what he's saying.
For me, I found the movie to be very entertaining. I watched it with my family, even though swear words continued despite the good Captain's reminder to watch it.