There is nothing wrong with treating non-Muslims kindly if they are not fighting us

There is
nothing wrong with showing kindness to non-Muslims, so long as they are not
known to be hostile towards Muslims or to be helping our enemies against us.
Allah, may He be exalted, says (interpretation of the meaning):

“Allah does
not forbid you to deal justly and kindly with those who fought not against you
on account of religion and did not drive you out of your homes. Verily, Allah
loves those who deal with equity.

It is only
as regards those who fought against you on account of religion, and have driven
you out of your homes, and helped to drive you out, that Allah forbids you to
befriend them. And whosoever will befriend them, then such are the Zalimoon (wrong-doers those who disobey Allah).”

[al-Mumtahanah 60:8-9].

Ibn Katheer
(may Allah have mercy on him) said:

That is, He
does not forbid you to treat kindly those disbelievers who are not fighting you
because of your religion, such as the women and the weak among them.

“deal justly” means to treat them kindly

“and kindly” means fairly.

“Verily,
Allah loves those who deal with equity”. End quote.

Tafseer Ibn Katheer, 4/446

Shaykh Ibn
‘Uthaymeen said in his commentary on Soorat al-Baqarah
(2/294):

With regard to
non-Muslims, there is nothing wrong with treating them kindly on condition that
they are not among those who are fighting us because of our religion or seeking
to drive us from our homes, because Allah, may He be exalted, says
(interpretation of the meaning):

“Allah does
not forbid you to deal justly and kindly with those who fought not against you
on account of religion and did not drive you out of your homes. Verily, Allah
loves those who deal with equity.”

[al-Mumtahanah 60:8].

The Muslim
will be rewarded for treating these people kindly. Allah, may He be exalted,
stated that one of the attributes of the righteous, who are the people of Paradise, is (interpretation of the meaning):

“And they
give food, in spite of their love for it (or for the love of Him), to Miskin (poor), the orphan, and the captive”

[al-Insaan 76:8]

–and the
captive cannot be anything other than a non-Muslim.

Qataadah (may Allah have
mercy on him) said:

“And they give
food, in spite of their love for it (or for the love of Him), to Miskin (poor), the orphan, and the captive”

[al-Insaan 76:8]

–Allah has enjoined kind treatment of captives, and the captives at that
time would have been mushrikeen (polytheists).

See: Tafseer at-Tabari,
10/8364

An-Nawawi (may Allah have mercy on him) said in al-Majmoo‘ (6/237):

If you give
charity to an evildoer or to a non-Muslim such as a Jew, a Christian or a Magian, that is permissible and there will be reward for
that in general terms. The author of al-Bayaan
said: as-Saymari said: The same applies with regard
to a non-Muslim who is in a state of war with the Muslims. The evidence for
that is the verse in which Allah, may He be exalted, says (interpretation of
the meaning): “And they give food, in spite of their love for it (or for the
love of Him), to Miskin (poor), the orphan, and the
captive” [al-Insaan 76:8], and it is well known
that the captive would be a non-Muslim who was in a state of war with the
Muslims. End quote.

And Allah knows best.