to say what is written in God's Word is
not "a false gospel":
John 1:29 The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world.
John 3:16-17 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. For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
2 Corinthians 5:19 To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation.
1 John 2:2 And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.
Under your erroneous dogma, you have to add to Scripture ... words ("elect") / concepts (we "do not have to believe it, accept itor do anything but continue being ungodly sinners") ... never intended by the Author of Scripture as if God needs you to explain what He means.
Just read Scripture as written and let God work in your heart to bring understanding. The
whole world is the
whole world.
The sacrifice of the Lord Jesus Christ is sufficient to cover the sins of all mankind ... each and every descendant of Adam ... whether born prior to or after the crucifixion of the Lord Jesus Christ.
Under your erroneous dogma, the sacrifice of the Lord Jesus Christ was lacking ... was somehow insufficient to cover the sin of
all mankind.
There is only one sin for which there is no forgiveness ... reject what God has so freely poured out ... those who suppress the truth in unrighteousness (Rom 1:18) reject God.
Excerpt from "What is the unpardonable sin / unforgivable sin?"
The only unpardonable sin today is that of continued unbelief.
There is no pardon for a person who dies in his rejection of Christ. The Holy Spirit is at work in the world, convicting the unsaved of sin, righteousness, and judgment (John 16:8). If a person resists that conviction and remains unrepentant, then he is choosing hell over heaven. “Without faith it is impossible to please God” (Hebrews 11:6), and the object of faith is Jesus (Acts 16:31). There is no forgiveness for someone who dies without faith in Christ. God has provided for our salvation in His Son (John 3:16). Forgiveness is found exclusively in Jesus (John 14:6).
To reject the only Savior is to be left with no means of salvation; to reject the only pardon is, obviously, unpardonable.
https://www.gotquestions.org/unpardonable-sin.html