Joh 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever
believeth in him should not perish, but have everlasting life.
It must be an ongoing living, abiding, present tense faith. Some believed for awhile, and then ceased to do so:
Luk_8:13 They on the rock are they, which, when they hear, receive the word with joy; and these have no root, which for a while believe, and in time of temptation fall away.
Now, watch the OSAS'e re-write Luke 8:13 by definition, rather than word. It doesn't say these never believed.