No one says these other religions are sure vehicles to salvation. That's not the point or thrust of the statement. We're talking here about what these other religions teach as facts, not whether they teach in a way that leads to salvation. Any religion teaching that deity exists, or that it's wrong to kill or steal, has got at least THOSE things "right." They do! Those are facts, it's silly to say otherwise. But that's no endorsement of their whole package, and you certainly should know that. it's a straw man agrument otherwise.
WRONG! Unless that Diety is the God of the Bible, then that religion is in violation of the First Commandment. Anything that follows that is false religion. Those other religions may teach that it is wrong to do certain things, but that does not mean that there is any "Truth" in them. They start out with a false premise.