Fine . . .
Quran (5:33) -
"The punishment of those who wage war against Allah and His messenger and strive to make mischief in the land is only this, that they should be murdered or crucified or their hands and their feet should be cut off on opposite sides or they should be imprisoned; this shall be as a disgrace for them in this world, and in the hereafter they shall have a grievous chastisement"
I guess first tell us if this is an accurate translation of the verse?
If so, then explain how this is not an evil tenet and a threat to the West (if not everyone not Muslim)?
First yes it seems to be a translation. from Quran.com Sahih International follows-
Indeed, the penalty for those who wage war against Allah and His Messenger and strive upon earth [to cause] corruption is none but that they be killed or crucified or that their hands and feet be cut off from opposite sides or that they be exiled from the land. That is for them a disgrace in this world; and for them in the Hereafter is a great punishment,
http://www.quranicpath.com/finerpoints/cut_hands_feet.html
https://discover-the-truth.com/2014/10/05/quran-533-the-punishment-of-those-who-wage-war/
http://www.islamicstudies.info/tafheem.php?sura=5&verse=33&to=34
3 sites by google "5:33 explained".
These in and of themselves explain the various meanings. One must realize there is a physical aspect of it and a spiritual, therefor multiple conclusions can and will be coming out of each Aya, each being true. However to come to the conclusion such as your source material does, they have forgotten (or more truthfully neglected) that the Quran is an entire book, not just 1 Aya. But for argument sake let's take a look at the literal, without context...
Indeed, the penalty for those who wage war against Allah and His Messenger
Here we already have a very specific description. "Those who wage war against Allah" could be easily construed as this Terroristic nonsense uses in their talk of holy war, but that's not what it says is it? It includes those at WAR with Allah's Messenger (PBUH). The Union "and" means both have to be true. Obviously Mouhammed (PBUH) is not alive any longer, so that would be quite difficult to wage war against him. But for argument sake, we will bypass this and apply it to all who wage WAR against Islam (because that's what you are fearful of isn't it, that you will be seen as being at war with Islam?)
To strive, means actively try. You are actively putting effort into it.
Without going into too much Quran, this can seem vague. But we can suffice to argue that this refers to spreading false rumors and lies about Allah and his Messenger (PBUH) in this Aya. Things such as declaring "The Quran says to chop everyone's hands and feet off" but knowing otherwise. Causing people who do not know or are weak in knowledge of Quran to believe such. This also covers those who kill followers for the sake of trying to show they have no protection.
is none but that they be killed or crucified or that their hands and feet be cut off from opposite sides or that they be exiled from the land.
Here we come to the judgements a Judge may order. In the case of the Aya, the Judge would have been the Prophet (PBUH) or at least someone close to him. Now I realize the drivel out there about his character, but most Hadiths show 1 attribute to Mouhammed's (PBUH) judgements, Mercy. Allah prescribes Mercy and Forgiveness above all. So we see here a series of punishments available. The order they are given is of great significance also. People tend to focus on the last thing most, which is why when someone presents things they normally go from least to most shocking... "The monster was green, large as 10 men, with glowing eyes, claws like razor blades, and breathing Fire!!!" . In the Aya however we go from killed (Very serious), Crucified (still alive, but in extreme pain), hands and feet of opposite sides cut off (still alive pain goes away, reminder remains), exiled from land (Move away? that's it?).
That is for them a disgrace in this world;
Explains that that is the punishment for this world. Men are allowed to issue these judgements of punishment.
and for them in the Hereafter is a great punishment
but their punishment in the hereafter is worse, but that is for Allah to decide.
So unless you are at war with Islam (or more accurately Allah and his Messenger (PBUH)) and spreading lies knowingly or killing followers for the sole reason that they are Muslims, you have nothing to fear of these consequences.
Does this suffice to answer your query?