3 This is now the second letter that I am writing to you, beloved. In both of them I am stirring up your sincere mind by way of reminder, 2 that you should remember the predictions of the holy prophets and the commandment of the Lord and Savior through your apostles, 3 knowing this first of all, that scoffers will come in the last days with scoffing, following their own sinful desires. 4 They will say, “Where is the promise of his coming? For ever since the fathers fell asleep, all things are continuing as they were from the beginning of creation” (2 Pet 3:4).
i) The Bible doesn't have much to say about atheists. That's in large part because the ancient world was very religious. And while there were undoubtedly some closet atheists or agnostics, it was politically hazardous to dis the state religion or undermine a lucrative industry (cf. Acts 19:23ff.).
You had some pockets of religious skepticism in Greco-Roman philosophy. But NT writers had little occasion to comment on that.
ii) Ancient religious skepticism wasn't necessary a bad thing. It was directed against pagan superstition. Heathen divination. Moreover, most pagans had little precious little evidence that the gods actually intervened in human affairs. Did prayer to Baal or Juno really make any tangible difference?
iii) It's not possible to reconstruct Peter's opponents with certainty. From what he says about the false teachers, their position has some affinities with Epicureanism. However, heretics don't necessarily have a coherent position. The position of the false teachers may have been a ragtag affair, with no philosophical consistency.
iv) Apparently, the false teachers call themselves Christian. They have infiltrated some Christian communities. Their background is gentile.
Although there's a danger of drawing excessive inferences from Peter's scanty descriptions, their position seems to be deistic at best. It's not even clear if they believe in divine creation. "Creation" may simply refer to the chance origin of the world. In any event, they apparently reject divine providence and miracles. Their position borders on atheism. A noninterventionist God is scarcely distinguishable from a nonexistent God. At most the "ground of being".
v) One might ask how they could view themselves as Christian at all. Yet we have other examples of this. For instance, Leibniz and Maimonides have little room for miracles in their system. Bultmann viewed the universe as a closed system. Or take someone like Peter Enns, who denies many Biblical miracles. Indeed, he probably denies more miracles than he lets on to.
There are different ways to finesse that in relation to Scripture. Some people allegorize the miraculous accounts in Scripture. Others outright deny all or most Biblical miracles, but claim that's inessential to what Christian faith is ultimately about, viz. Schleiermacher, Tillich, Don Cupitt, D. Z. Phillips, Bishop Robinson.
vi) This is where evidence for modern miracles can be useful. Even for true believers, it can sometimes feel that we are waiting for something that never happens. Is it just wishful thinking? So it's helpful to have some well-attested examples of divine intervention above and beyond what Scripture reports. And it doesn't take much to disprove a universal negative. Even a little encouragement is logically sufficient.