here is the scripture
Rev 21:8 But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
And "fearful" here means just that - timid or fearful
Timidity implies either a complete lack of belief, a shame of it, or an unpreparedness.
Be strong in Christ! Shine for him!