Your parents are always your parents, no matter what they believe or do. And the Bible, as you know, tells us to honour our parents. We may differ from them in beliefs, but as long as we are under their roof, there is not much that can be done, but respect, honour and obey them. You can respectfully give your parents your point of view, but they may of course differ and insist that they are correct, and you are wrong.

Exodus 20:12   “Honor your father and your mother, that your days may be long upon the land which the Lord your God is giving you.”

When you are still underage, you have to obey them, or at least ask them if you can live according to your own beliefs. But if they refuse, there is very little that you can do but obey, until you are old enough to go out on your own and live your own life. But never stop praying for them, asking God to speak to their hearts and change them, or at least for them to let you live in the way that you believe is right. Pray also that God will help you to live in a way that will show God working in you, so that your parents will want to change and be like you.

Proverbs 3     ⁵ Trust in the Lord with all your heart, and lean not on your own understanding; ⁶ In all your ways acknowledge Him, and He shall direct your paths.

1 Thessalonians 5     ¹⁶ Rejoice always, ¹⁷ pray without ceasing, ¹⁸ in everything give thanks; for this is the will of God in Christ Jesus for you.

As far as showing them the truth, you should be asking God to impress you to tell you when the time is right, and exactly what to say. Don’t just barge in and tell them that they are wrong, because that is not the way to do it. Work on your relationship with God, spend lots of time in prayer, and study your Bible, so when you do get the chance to speak to them, you will be properly prepared.

Keep on praying, and I will pray for you and your parents as well. God bless!