How is sinning judged after accepting Christ?

Generally speaking, a sin is a sin, is a sin, whether or not the individual is a believer. The difference is that believers are forgiven and are accepted by God because they have Christ's righteousness "imputed" to them by faith. (See "Sola Fide," "Salvation by Grace through Faith").

Romans 3:23 is one text often offered as proof that, from a biblical perspective, all people are guilty of sin. Many denominations also teach that Christians necessarily continue to sin, even after they are saved (see Mat 5:21-30). (A notable exception to this is found in the Methodist doctrines of "Christian Perfection," taught by the Wesley brothers in the eighteenth century). Romans 7:13-25 is another text often offered as proof that believers continue to sin -- it is frequently interpreted as teaching that Paul recognized sin in himself, post-conversion. See also Romans 6.

The basic notion of forgiveness in Christianity is that all human beings are guilty of sin, and there is no way that we can earn our way into heaven by doing good deeds; once we've committed one sin, we're as guilty as if we had broken every law in the book (see James 2:10). In order to glorify himself, God has chosen to have mercy on some sinners and save them, but since he is perfectly just, someone had to be punished for the sins that had been committed by the people he chose to save, and that person could only be one that had not first incurred his own debt of sin. So, God punished sinless Christ, and -- without getting into doctrines like election, free will, universalism, monergism vs synergism, etc. -- he applied that atonement to believers, who are then seen "in Christ" as sinless and so are accepted by God.

One common point of confusion is the notion that "all sins are equal." There is a wide consensus that such is not the case, though there are those who will argue the point. A simple Google search on "are all sins equal" will return a wealth of results, so I won't elaborate further here, except to clarify the basic idea. (BTW, remember to consult only credible, verifiable sources, whichever perspective they advocate). While some sins are, in God's sight, worse than others, as soon as a person has committed one sin of any sort, they have become "unclean," and are permanently barred from heaven. God takes sin so seriously that all sin must be punished, and the punishment associated with any one sin is such that it could only be paid by Christ. That being said, it is possible for one person to incur a greater "sin debt" compared with another, but in any case, all sin is forgiven when one receives Christ. (Note that there is reference in the NT to something called the "unforgivable sin," which is a weighty and contentious doctrinal issue in and of itself).

See the Westminster Larger Catechism, questions 150 - 153.

Some denominations teach that a saved person can "backslide" and become involved in sin, and that such a person needs to be "restored." Other denominations teach that the presence of "significant," or ongoing, repetitive sin in one's life is a potential indication that one was not truly saved in the first place, since regeneration places the love of God in one's heart, and sin both angers & grieves God. Some teach that once a person is truly saved, he can never become "unsaved" (see "Perseverance of the Saints," "T.U.L.I.P."); others believe that it is possible for a person to "fall away" and "be restored" many times.

It is also commonly taught that the rewards that individual believers receive in heaven will be commensurate with the righteousness of the life they lived on earth. The most commonly referenced reward that I have heard about relates to the "number of cities" that one will rule over in heaven. Some also teach that there are varying degrees of punishment in hell. Some examples of passages that are offered by those who support such teachings are the parables at Luke 19:11-27 and Luke 12:47-48.

Addendum: I thought about this topic some more, and it brought to mind something called the "Lordship Salvation Controversy." It's been some time since I looked into this area of soteriology, but one thing that hasn't changed in the intervening years is the caustic nature of most of the internet discussions on the topic. (Btw, for times like these, it can be useful to bear in mind Paul's exhortation to Timothy in 2 Timothy 2:22-26).

"Lordship salvation" refers to one doctrine that claims to describe specifically what God requires of his followers. The alternative doctrine is sometimes called "Non-Lordship Salvation," or, disparagingly, "easy believism." I don't feel qualified to attempt a concise summary of the issues, but here are some links that I've tried to vet for you. I encourage you to use caution in consulting the links that result from a "lordship salvation" internet search, as many of them seem to be filled with invective.

Some useful links:

1. I'm very familiar with the ministries of John Piper (Desiring God) and RC Sproul (Ligonier) . Both are well educated, compassionate men, with strong understandings of Reformed theology.

   • John Piper from Desiring God Ministries on Lordship Salvation. (Long list of scripture proofs).
   • Articles tagged "Lordship Salvation" in the Resources section of Ligonier Ministries' site.
   • Devotionals tagged "Lordship Salvation" in the Resources section of Ligonier Ministries' site.
   • More content from Ligonier.

2. Here's a site called "Monergism." Monergism is actually the name of a doctrine, and the site staunchly advocates in favor of their viewpoint, but does so in an intelligent way. In reviewing their extensive list of links on Lordship Salvation I recognized some credible names with historic significance.

   • Resources at Monergism.com.

3. I'm not particularly familiar with Theopedia. A quick look over their pages on Lordship Salvation and Non-Lordship Salvation throws up no immediate red flags. It looks like they link almost exclusively to contemporary teachers for their references, at least for this topic.

   • Theopedia entry for "Lordship Salvation."
   • Theopedia entry for "Non-Lordship Salvation."

4. And here's a link to a discussion from a few months ago (early 2012) that includes what looks like some intelligent comments on the issue:

   • PuritanBoard.com discussion on Lordship Salvation, Feb 2012.

Hope this doesn't seem overwhelming. There's probably enough resources in this post to get started on a dissertation! The teachings of RC Sproul and John Piper are normally very accessible, and a great place to start if you're new to a topic and like a Reformed perspective. Cheers.