Q: Are all transgressions of the law equally heinous?
A: Some sins in themselves, and by reason of several aggravations, are more heinous in the sight of God than others.

Ezekiel 8:6. He said furthermore unto me, Son of man, seest thou what they do? even the great abominations that the house of Israel committeth here, that I should go far off from my sanctuary? but turn thee yet again, and thou shalt see greater abominations.
Ezekiel 8:13. He said also unto me, Turn thee yet again, and thou shalt see greater abominations that they do.
Ezekiel 8:15. Then said he unto me, Hast thou seen this, O son of man? turn thee yet again, and thou shalt see greater abominations than these.
1 John 5:16. If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.
Psalm 78:17. And they sinned yet more against him by provoking the most High in the wilderness.
Psalm 78:32. For all this they sinned still, and believed not for his wondrous works.
Psalm 78:56. Yet they tempted and provoked the most high God, and kept not his testimonies.
Psalm 19:13. Keep back thy servant also from presumptuous sins; let them not have dominion over me: then shall I be upright, and I shall be innocent from the great transgression.

Westminster Project - See John Flavel for more information on the 83rd question of the WSC