A common Hebrew expression is "Respect them and suspect them". We should always act in a respectful way towards others, but that doesn't obligate us to trust them with our property. The source of this is in a story of the Talmudic sage Rabbi Yehoshua. A complete stranger asked to stay the night. Rabbi Yehoshua obliged him by giving him a room in the attic, but also exercised prudence by removing the ladder so that the guest wouldn't be able to sneak out. The guest turned out in fact to be a thief; he wrapped all the valuables in the top floor in a cloak and tried to sneak out, but fell in the dark because of the missing ladder, and was caught red-handed.
Do we have an expression in English to this effect?
the expression has been ascribed to V. I. Lenin, not our first choice among icons of liberty. However, these words seem to encapsulate the purported defence of our freedoms, by elected governments on both shores of the Atlantic.