Why did God create us with a sin nature?

God cannot create unlike ‘Himself’. That is all that is created is perfect .

The whole idea of sin was invented by man out of guilt. The guilt was created by the separation from God. But it is illusory.

i think thats why he did it

I was brought up Roman Catholic. This is the way it was explained to me.

Sin came with the knowledge  of good and evil, This is the result of Adam and Eve's eating from the tree of knowledge. We now have free will to choose  between good a d evil. That's not the same as having what you call " a sin nature".

Whether we know God or not, we humans cannot not sin. It's not possible to go an entire day without sinning by thought, word, or deed. That's our plight and the reason for a Savior. We're trapped, stuck, shackled, a slave to our own desires and ambitions.

wrong WE WERE PERFECT TILL WE SINNED....WE ALL HAVE FREE WILL TO CHOOSE EITHER GOD or the devil...ANYONE CAN PRAY WHEN WILLING.

Isaiah 43:7 "I created man for my glory." Compare Eccl. 12:13, John 4:24.

Why is it a sin for humans to have intimate relations, as animals naturally do?  Also, why is it a sin to seek out knowledge, which was represented by the apple?

He didn't create us with it. We rebelled and obtained it. God gave us the ability to freely choose, and we chose to rebel. Yeshua made atonement for us which grants us the opportunity to become a NEW creation in Him.

He didn't. He created us as He is, innocent and perfect. But he also gave us choice t o live that way or experiment other ways. This is one of those experiments. We can get out of it by asking for His truth again.