And harming yourself is a sin.
I don't believe you need to be religious to know when something is a crime that harms others or a vice that harms yourself - and possibly others, that it is part of nature to know it.
I simply believe that you want to get rid of your sins and vices after you are saved. That you repented of them before, and they are an unnecessary burden.
There is a deep need to know God in man's heart, and no way that natural man knows how to do it. He feels despair. He feels God doesn't listen, doesn't care. And he feels bad that he is going to die someday. "So let us eat and drink today, for tomorrow we die" (1 Corinthians 15:32).
And then he discovers that God really does love him. That there is a way for him to know God. That God has made a provision and way for him to be saved. And that way is Jesus Christ. He hopes. He prays; and he is saved by God Himself. He is filled with hope and joy where there was sin and despair. He has been set free from the bondage of sin, and given everlasting life.
And for the support of this Declaration, with a firm reliance on the protection of Divine Providence, we mutually pledge to each other our lives, our fortunes and our sacred honor.