I prefer the KJV here:
Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice,
The word here is thaumazo, which has a gloss "to marvel, be astonished". From BDAG:
to be extraordinarily impressed or disturbed by someth., act. ⓐ intr. wonder, marvel, be astonished (the context determines whether in a good or bad sense)
Whereas "amaze" in modern english has taken on a somewhat softer meaning and can be used to refer to everything from an impressive display of fireworks to the more traditional notion of being astonished or surprised. E.g. we are not surprised by an impressive fireworks display on the fourth of July because we expect it, even though the experience itself is still amazing. It is precisely this element of surprise that Jesus was addressing, telling us not to be surprised because he will call out the dead from their graves, and thus the power of God working through Christ should not be something that surprises the disciples, although we are free to continue being impressed by this power.
 Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 444). Chicago: University of Chicago Press.