When should someone no longer be allowed to frequent a masjid?

When is it justified to let someone know that they are no longer welcome at our masjids?

Are we to tolerate someone whose beliefs are 100% aligned with the Quran, yet their behavioral conduct is that of an aggressor or tyrant?

For such people God tells the believers that it is their duty to fight the aggressing group.

[49:9] If two groups of believers fought with each other, you shall reconcile them. If one group aggresses against the other, you shall fight the aggressing group until they submit to GOD’s command. Once they submit, you shall reconcile the two groups equitably. You shall maintain justice; GOD loves those who are just.

Or should we welcome someone whose behavior is 100% aligned with the Quran, yet their beliefs are openly in defiance to the teachings of the Quran?

For such people, God informs us that as long as they don’t fight us and they mobilize in the cause of God along with us we can still even consider them friends.

[4:88] Why should you divide yourselves into two groups regarding hypocrites (among you)? GOD is the one who condemned them because of their own behavior. Do you want to guide those who are sent astray by GOD? Whomever GOD sends astray, you can never find a way to guide them. [4:89] They wish that you disbelieve as they have disbelieved, then you become equal. DO NOT CONSIDER THEM FRIENDS, UNLESS THEY MOBILIZE ALONG WITH YOU IN THE CAUSE OF GOD. If they turn against you, you shall fight them, and you may kill them when you encounter them in war. You shall not accept them as friends, or allies.

But the verse that some abuse to justify the extreme of banishing someone strictly for their belief is the following:

[9:17] The idol worshipers are not to frequent the masjids of GOD, while confessing their disbelief. These have nullified their works, and they will abide forever in Hell.

By simply labeling whoever they want as an idol worshipper it is as if some have found a loophole in God’s system, but is this how the verse should be interpreted?

If we read these verses in context, the group of idol worshippers that are consistently in reference in this entire sura are those that are of a separate idol-worshipping community that are at potential war/opposition with the believers. (9:1, 3, 4, 5, 6, 7, 17, 28, 31, 33 36, 113).

Additionally, these are not members of an existing community who simply have a difference of understanding on some Quranic topic, but individuals whose Shahadah is different than that of God’s, the angels, and the knowledgable.

I come to this understanding because the Arabic that is used for “confessing” is شَاهِدِينَ (shāhidīna) which is the same root as Shahada (3:18). Therefore, 9:17 is in reference to known idol worshippers of opposing communities whose intent for attending the masjid of God is to openly declare their false shahadha.