“christians” who pick & choose what they wanna believe in from the bible aren’t real christians lol

I'm not for sure if Christians actually have different beliefs on what is sin and what is not sin. The Bible is quite clear it names the sins and all things that fall in those categories.

The greatest sin is blasphemy

Because sin separates us from God it is viewed sins are equal but

There are indeed some sins greater than others example between murder and gluttony.

John 19:11 Jesus said to pilate he who delivered me unto you has the GREATER SIN

Some sins are considered abominations to God, proverbs 6:17-19.

Actually there in a sin greatr then all others.. Blasphemy of the Holy Spirit.. Because Jesus declared that it would never be forgiven... All other sins are forgivable through the Atonement of the LORD Jesus..

Does it really need a ‘ there?

That's literally every religious person.