Below are a couple Samuel Rutherford quotes on civil sanctions for heresy. Taken from his book A Free Disputation against pretended Liberty of Conscience.
"All the question is concerning the imperated acts and these external, that is not touching opinions and acts of the mind, but that which is visible and audible in these opinions, to wit, the speaking, professed holding of them, publishing, teaching, printing, and known external persuading of others to be of our mind.... It is clear the question must be thus stated, for all the laws of the old Testament (which we hold in their moral equity to be perpetual) that are touching blasphemies, heresies, solicitation to worship false Gods and the breach of which the Godly Magistrate was to punish, command or forbid only such things as may be proved by two or three witnesses, and which husband and wife are not to conceal, and from which all Israel must abstain for fear of the like punishment. Deut. 13.8, 9, 10, 11. Deut. 17. 5, 6. Levit. 20. 1, 2, 3, 4, 5. But opinions in the Mind, acts of the understanding, can never be proved by witnesses and such as neither Magistrate nor Church can censure." Free Disp. Ch. 4, 46, 47.
"These are of a wide difference, [for civil rulers] to kill blasphemers, and false teachers for spreading heresies and blasphemies; and to compel them by war, and fire and sword to be of our Christian religion." Free Disp. Ch. 4, 53.