It is not untrue, the resurrection is how and when you are truly saved. Until then it's faith, and faith is in things unseen. Plenty of people can say they are saved now, but they're just blowing wind, they probably don't even know what they're talking about, they're just repeating nonsense someone else told them. Seen plenty of people claim to be born again or saved, and then hours later go commit the sins unto the death; think they're telling the truth or think they're just really deceived?