Have you read I Don't Have Enough Faith to Be an Atheist?
Until someone comes up with a coherent explanation for how matter, or life, spontaneously came into existence, Materialists also believe in supernatural miracles. So I guess Materialists are "superstitious" by whatever criteria is being used. Thus, if we assume that what Christians are really being accused of is irrationality (or delusion), Materialists are being hypocritical.
It's not irrational or delusional to believe in miracles (i.e. "supernatural intervention") if such really occur(red). What's irrational is refusing to accept reality. If a miracle should occurs, it would be irrational to deny that it occurred. If the available evidence strongly suggests a historic miracle (e.g. the existence of the universe, or the existence of life), is it rational to insist on a world view that denies that miracles can occur?
Yet, this is the heart of Materialism.
...But you asked about if Christianity is "superstitious". Well, what is superstition?
A superstition is any belief or practice considered by non-practitioners to be irrational or supernatural, attributed to fate or magic, perceived supernatural influence, or fear of that which is unknown.
It should be blatantly obvious that Materialists are superstitious from a (biblical-historical) Christian perspective. One response is to simply point out this plain fact. Naturally, Materialists, desiring to control the rules in their favor, will simply deny this, but it doesn't change that they lack coherent explanations for various pillars of their beliefs, or that there are significant evidentiary problems with those beliefs.
If one wants to be pedantic, however, Christians are superstitious, in the sense of believing in the supernatural (that is, God, miracles, the resurrection of Christ, etc.). And so what? Defined that way, there's nothing wrong with superstition. What's "bad" is irrationality, a trait which is frequently more prevalent among Materialists than among Christians.