There is an explicit offer of forgiveness in the second part of the tweet. Whether his use of "death penalty" refers to a specific government punishment, or more generally to the "wages of sin" is somewhat ambiguous (it could have been made a bit more clear if he included some "lesser" sins in there like lying/perjury, theft, or covetousness, but I can see why you wouldn't include those on a twitter post.) And if you don't believe that the death penalty is an appropriate punishment, I can find citations from the New Testament that support this as being one of the roles of government.

Irrespective, I find no contradiction between the idea that the proper government penalty for a crime should be death, and that we should offer forgiveness and a second chance to repentant souls.