Continuing with the second half of the level 1 cleric spell list.
5. Protection From Evil: At first blush, this spell, granting +1 to saving throws and -1 to attack rolls against attacks from creatures of an alignment different from the cleric's, looks basically like a buff spell, and a pretty cheesy one at that. If that were all that it did, it would be a near-total waste of a spell slot. The spell's real power lies in the second effect listed: It completely blocks "enchanted" creatures from attacking the caster in melee. The Mentzer rules offer further clarification of the "enchanted" qualifier: any magically summoned, animated, or controlled creature, and any creature that can only be hit by magic weapons. That means all golems, living statues, gargoyles, and other magical constructs, conjured elementals, invisible stalkers, zombies and skeletons, charmed and geased creatures, spectres, vampires, and shadows. A good many of those creatures don't even have any non-melee attack forms. A cleric could literally wade through a pit full of them in perfect safety, or interpose himself between hostile enchanted creatures and a vulernable companion. The cleric may use spells, turning, and missile attacks without breaking the protection. And it lasts a full 12 turns!
6. Purify Food and Water: This is one of those spells that requires the DM to apply and keep track of factors for which there are no clear rules provided in order to be useful. Rations and skins of water must be tracked closely, so that characters face a potential need for provisions found in the field, which may not be suitable for consumption in their present state. There must be penalties imposed for going without food and water, and for ingesting spoiled or tainted food and drink. Either that, or you need players who are firmly committed to role-playing the effects of thirst, hunger, and food poisoning despite there being no mechanical incentive for them to do so. Most players in my experience aren't that dedicated. Nonetheless, with a little effort on the part of the DM, this spell could play an interesting role in the resource management aspect of the game. If resource management doesn't add to the game's fun for you, this spell probably doesn't belong in it either.
7. Remove Fear*: There aren't a whole lot of things in B/X D&D that cause fear that has actual game effects. In a party of all PCs, its only real use is as a counter to its own reversed version. It might be useful when mounts, animal companions, or NPC henchmen fail a morale check, though. It would be nice if the spell gave a bonus to, or even automatic success with, tasks that are difficult mainly because they're frightening - walking across a narrow plank over a bottomless chasm, for instance. Adding other save-or-fear effects to the game would also make the spell more useful. A serious drawback is that the range is 0 (touch), so if a creature is already running scared, the cleric better be prepared to chase and intercept it. Also, a creature under a magical fear effect only receives a second saving throw (with a bonus equal to the cleric's level) so it may fail anyway.
The reversed spell, Cause Fear, causes the target to flee in fear if a saving throw vs. spells is failed. Unlike the standard version, Cause Fear has a range of 120', so no need to be in melee range to use it. It affects only one target, but Spells is generally the hardest category of saving throws, so the odds are pretty good that it will take that target out of a fight. Successully using it on an enemy leader might well break the morale of his troops, too, and save the entire party some fighting. That's a lot more bang for the spell slot than, say, Cause Light Wounds.
8. Resist Cold: There's not really a lot in the rules-as-written to make this spell attractive. White dragon breath and the Wall of Ice spell are really the only things it's useful against, and the saving throw bonus and damage reduction are fairly trivial. I guess that's not too unreasonable for a 1st level spell, but that narrow range of utility makes it hardly worth expending a spell slot. Theoretically it makes the subject completely immune to non-magical cold too, but the game provides no rules for harm from non-magical frigid conditions. House rules for those conditions, or just ad hoc situations on a dungeon or wilderness key that provide instances of harmful cold, could make it a worthwhile spell.
And that's it for 1st level cleric spells. Next up, I'll jump over to the magic-user spell list.