Well of course were one to state something that isn’t true to God’s word then they would be opposing what God has said...so either God or the individual is not telling the truth. Thus a liar. But saying something that is not true does not send a person to hell by any means.....it’s rejection of the finished work of Jesus Christ that dooms people for they’ve chosen not to believe He gave His life for them...and paid the jugement for their sins.
As ‘believers’ our judgement will be of rewards, not condemnation. It will be a judgement of condemnation for those without Christ Jesus.
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.