It is not a false gospel to proclaim that Jesus Christ died and resurrected on the behalf of those, who will CERTAINLY be justified by faith alone. John 3:16
It would be a false gospel to proclaim that Jesus Christ died for all men everywhere, if only they will choose to believe and accept the salvation He only made POSSIBLE for them.
Christ DID die for the sins of ALL Humanity. However, ONLY those who place ALL their faith in Christ alone as their Savior will be saved and inherit eternal life. Those who reject God's Gift to humanity are awaiting judgement and eternal damnation in the Lake of Fire.