100:1 Make a joyful noise unto the LORD, all ye lands.
100:2 Serve the LORD with gladness: come before his presence with singing.
100:3 Know ye that the LORD he is God: it is he that hath made us, and not we ourselves; we are his people, and the sheep of his pasture.
100:4 Enter into his gates with thanksgiving, and into his courts with praise: be thankful unto him, and bless his name.
100:5 For the LORD is good; his mercy is everlasting; and his truth endureth to all generations.
The verse centers on "mercy", "sheep", "make", "joyful", "noise", "lord", "lands", and "serve". It is saying that the verse draws attention to "mercy" and "sheep", so its meaning should be read from those terms before moving to application.
The local KJV text gives this verse as the immediate unit, so "mercy" and "sheep" carries the first interpretive weight. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "mercy" and "sheep" with trust shaped by these words, not by a vague optimism outside the passage.