The Christian Perspective
There is no other logical possibility.
Either some things are caused, or nothing is.
If nothing is caused, then I never wrote this. But I did write this, so at least some things are caused.
If some things are caused, either their causing is the result of a previous cause, or it isn't. In other words, either something caused it to cause, or nothing caused it to cause.
If every cause is the result of a previous cause, or, if everything is caused by something else, then we have an "infinite regress" of causes.
An infinite regress of causes is logically incoherent. To suggest that there have been an infinite regress of past causes is to suggest that we have come to the end of an infinite series. An infinite series, however, is by definition a series with no end. So this would mean that we have come to the end of a series with no end, which is logically incoherent.
Infinite regress would mean that we have iterated, one-by-one, through every single item of an infinite series. But an infinite series always has more items than those that have been iterated through. We would have iterated through something that cannot be iterated through, which is logically incoherent.
If we were to go backwards through each previous cause, and there were an infinite number of past causes, there would necessarily be some cause in the set of previous causes that we would never, ever get to. If that were not the case, it would not be infinite. If there is some supposed prior cause in the set of previous causes that we could never get to while iterating backwards through all previous causes, then, iterating forward from that cause to the present state, we would never arrive at the present state for the same reason that going backwards we could never arrive at the previous state -- namely, the infinite (or unending) number of causes in between the two.
Infinite regress would mean that we have completed something that cannot be completed. We have traversed something that cannot be traversed. We have itemized what cannot be itemized, counted what cannot be counted, spanned what cannot be spanned.
Infinite regress is logically incoherent. Therefore, not everything is caused by a previous cause.
This means, necessarily, that EVERY series of causes has its own first cause, and since this first cause is a FIRST cause, it is uncaused.
What we also see is that since this first cause is never the result of a prior cause, since it is in fact a FIRST cause, it does not cause involuntarily. In other words, nothing made it cause: it did it voluntarily -- on its own. The first cause, in every series of causes, is therefore necessarily volitional: it is willful; it has personhood.
Every uncaused first cause, since it is uncaused, either began to exist without cause, or else it did not begin to exist, and is therefore self-existent.
If it began to exist without cause, then having nothing, adding nothing to it, something results. Or, in other words:
0 + 0 > 0.
This is the same as claiming that zero is not zero, which is logically contradictory. I like to call this "Atheist Math".
Therefore, since nothing can be caused by nothing, every uncaused first cause is self-existent. It is eternal, permanent, and not subject to change over time. It simply... is.
When anyone talks about some kind of uncaused, self-existent, willful, eternal, personal entity that is the first cause of things, the label generally applied to such an entity is "God".
So we see that not only must some type of God necessarily exist because of the impossibility of the contrary, but also that He must be an uncaused first cause for the same reason.
In fact, Christianity is the only worldview that is logically coherent. All other worldviews fall victim to inherent logical contradictions within their most basic presuppositions, particularly wherever they diverge from Christianity.
For example, due to the lack of divine sacrificial substitutionary atonement in Islam, when Allah, who is always just, forgives, He is not just.
Due to the prophecies of the Messiah in the Hebrew Bible, Jewish prophecy is rejected by the Jews.
Due to the multiplicity of disagreeing gods in polytheism, wherever there is divine disagreement, things are and are not at the same time and in the same way.
The Christian God never contradicts Himself (2 Timothy 2:13); He fulfills the prophecies of the Jews (Acts 3:18); and the sacrifice of Christ makes it possible for the Christian God to be both just and forgiving at the same time (Hebrews 2:17).
Ultimately, only the Christian worldview provides a coherent understanding of reality and is not inherently contradictory.