"Eternity" was met with positive reviews from music critics. David Greenwald of
MTV stated, "The track gets some big-hearted vocals from
Owl City's Adam Young, who borrows a page from
Coldplay... The blinking four-on-the-floor beat strikes a balance between Young's breathy vocals and dance floor electricity, with the drums dropping out for the chorus before climbing back into the mix for a rave-y explosion." Scott Shetler of
PopCrush called the track a "dance song" that complements well with Young's vocals. He also added that Young was a "good fit" for the song. ==Music video==