“Whensoever your conscience shall tell you, that you have broken any of the Ten Commandments, do not conceive that the Lord looks upon you as an angry Judge, armed with justice against you.
Much less do you fear that He will execute His justice upon you, according to the penalty of that covenant, in unjustifying of you, or depriving you of your heavenly inheritance, and giving you your portion in hell fire.
No, assure yourself that your God in Christ will never unson you, nor unspouse you: no, nor yet, as touching your justification and eternal salvation, will He love you ever a whit the less, though you commit ever so many or great sins.
For this is a certain truth, that as no good either in you, or done by you, did move Him to justify you, and give you eternal life, so no evil in you, or done by you, can move Him to take it away from you, being once given.
And therefore believe it whilst you live, that as the Lord first loved you freely, so will He hereafter ‘heal your backslidings, and still love you freely,’ (Hos. 14:4).
Yea, ‘He will love you unto the end,’ (John 13:1).”
–Edward Fisher, The Marrow of Modern Divinity, as quoted in Thomas Boston, The Whole Works of Thomas Boston: An Explication of the Assembly’s Shorter Catechism, ed. Samuel M‘Millan, vol. 7 (Aberdeen: George and Robert King, 1850), 7: 353–354.