From what I've read, it seems that the majority of the abolition movement was driven by religious Christians. However, were there any notable abolitionists whom were personally secular or secularly argued against slavery?
The most prominent example that I can think of is probably Robert Green Ingersoll. He was only in his late twenties by the time the Civil War broke out so he hadn't fully developed his reputation as a speaker and advocate during the heyday of the movement, but he remained an advocate for closely related causes throughout his public life.
Here is a link to a speech he delivered in 1867:http://antislavery.eserver.org/legacies/address-to-the-colored-people
Can you provide the context of your question? I presume you are talking about American abolitionist movements?