Apparent endorsement of violence in the OT vs. “Love your Enemy” in the NT (Dt. 13 vs. Mt. 5) [closed]

The Book of Deuteronomy appears to endorse wholesale violence (murder?) against an entire city in punishment of a non-violent crime:

If you hear in one of your cities, which the Lord your God gives you
to dwell there, 13 that certain base fellows have gone out among you
and have drawn away the inhabitants of the city, saying, ‘Let us go
and serve other gods,’ which you have not known, 14 then you shall
inquire and make search and ask diligently; and behold, if it be true
and certain that such an abominable thing has been done among you, 15
you shall surely put the inhabitants of that city to the sword,
destroying it utterly, all who are in it and its cattle, with the edge
of the sword. (Deut. 13)

Is there a justification for this policy other than an appeal to supposed divine authority? Also, how can we reconcile this command with the teaching of Jesus that we should "turn the other cheek" and love our enemies?

38 “You have heard that it was said, ‘An eye for an eye and a tooth
for a tooth.’ 39 But I say to you, Do not resist one who is evil. But
if any one strikes you on the right cheek, turn to him the other
also… 43 “You have heard that it was said, ‘You shall love your
neighbor and hate your enemy.’ 44 But I say to you, Love your enemies
and pray for those who persecute you, 45 so that you may be sons of
your Father who is in heaven; for he makes his sun rise on the evil
and on the good, and sends rain on the just and on the unjust… 48
You, therefore, must be perfect, as your heavenly Father is perfect.

The apparent contradiction here is that in Mt. 5 we are taught to turn the other cheek and to love our enemies, while Deuteronomy teaches that we should kill them on a massive scale even though they have not engaged in violence against us.