Is it illegal for a parent to force you to be a religion you dont want to be?

No one's forced to believe anything. If you're in a situation that is hazardous to your safety, it's better to lie.

Obviously, indoctrination is very legal. Parents tell their kids what to believe all the time and they claim to "know" that their opinion is the truth. Some countries base their laws on religion.

Illegal, no. Nonsensical, yes. You cannot be a religion without a choice. You may be coerced to act as if you belong. That would be rational, legal, and something parents have done for generations.

Not illegal but certainly not taking your feelings into account. Unfortunately all you can do is discuss openly with them and hope they agree. If they are hardline then they will force you to keep going in the belief that it would eventually change your mind. Once you are older you can make your own choice, but for now you are at their mercy.

Your parents cannot force you to believe anything but they can insist that you attend church/synagogue/mosque/temple with them while you are in their care. Once you leave home you can do as you like. If you want to follow a different religion, discuss it with your parents but have good arguments to support your point of view. If you prefer atheism, the same thing applies.

I now many children who did not believe in the Holidays, religious or not birthdays etc.

and their convictions have remained the same all through out their adult lives.

But as children their parents were hated, children in schools and even their relatives try to convince them to celebrate them

But people claim it's a cult because of it.

If you are a minor, you have very little freedom and they choose a lot of things for you. Separation of Church and State makes it so that government can't make that illegal.

Minors can't properly think for themselves. If you let minors chose everything on their on, they'd ban homework by tomorrow.

Atheist logic... sigh.

Depends what you mean by "force"---if they are beating and starving you, then yeah, that's illegal.

If you're a minor, nope.

Make me to know thy ways, O Lord; teach me thy paths. Lead me in thy truth, and teach me, for thou art the God of my salvation; for thee I wait all the day long. (Psalm 25:4-5)

MARANATHA! Come, Lord Jesus, COME!

Unfortunately, no I agree; it isn't right, but there's nothing that can legally be done about it.