If you're happy, it's a sin?

If you're gay, you are synonymous to cheerful, gleeful, happy, glad, cheery, lighthearted, joyous, joyful, jovial; sunny, lively, vivacious, sparkling; chipper, playful, jaunty, sprightly, blithe.

But if you're NOT, you are the opposite: serious, grave, solemn, joyless; staid, sedate; unhappy, morose, grim; sad, depressed, melancholy.

In old English the word 'gay' in dictionary does mean happy. So, if you're happy, it's a sin?