If you want to know if you're a Christian, look at yourself, see your sins, and then look to Christ

Anyone who can look at himself and find reason for confidence before God is a liar, for we sin daily and much. And so a gospel which depends on us in any way is no Gospel at all.

Offered in response to someone looking at himself to know if he is saved:

You’re making up your own canon and not simply stating what God has revealed.

What did Paul say when he inspected his own fruit?

“I am of the flesh, sold under sin. For I do not understand my own actions. For I do not do what I want, but I do the very thing I hate [. . .] For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out. I do not do the good I want, but the evil I do not want is what I keep on doing” (Romans 7).

(The Greek for “keep on doing” is “prasso,” which means “to do habitually.”)

So, Paul hadn’t “licked” the “evil” he “hated” but committed it “habitually.” By your standard, he was no Christian.

What was Paul’s answer to this dilemma? “Wretched man that I am! Who will deliver me from this body of death? Thanks be to God through Jesus Christ our Lord!” (Romans 7).

What does Christ say about what we should see when we look inside ourselves? Should we see our good works, or should we see our sin and then . . . our Savior?

“Two men went up into the temple to pray, one a Pharisee and the other a tax collector. The Pharisee, standing by himself, prayed thus: ‘God, I thank you that I am not like other men, extortioners, unjust, adulterers, or even like this tax collector. I fast twice a week; I give tithes of all that I get.’ But the tax collector, standing far off, would not even lift up his eyes to heaven, but beat his breast, saying, ‘God, be merciful to me, a sinner!’

“I tell you, this man went down to his house justified, rather than the other. For everyone who exalts himself will be humbled, but the one who humbles himself will be exalted” (Luke 18).

God does not save those who are only imaginary sinners. Be honest about just how bad your sins really are, because Christ paid for them all. Here’s great news for the wicked, from Martin Luther [. . .]:

“If you are a preacher of mercy, do not preach an imaginary but the true mercy. If the mercy is true, you must therefore bear the true, not an imaginary sin. God does not save those who are only imaginary sinners. Be a sinner, and let your sins be strong, but let your trust in Christ be stronger, and rejoice in Christ who is the victor over sin, death, and the world.

“We will commit sins while we are here, for this life is not a place where justice resides. We, however, says Peter (2. Peter 3:13) are looking forward to a new heaven and a new earth where justice will reign. It suffices that through God’s glory we have recognized the Lamb who takes away the sin of the world. No sin can separate us from Him, even if we were to kill or commit adultery thousands of times each day. Do you think such an exalted Lamb paid merely a small price with a meager sacrifice for our sins?

“Pray hard for you are quite a sinner.”

Like the tax collector, St. Paul, and Martin Luther, when we look at ourselves, we should see our sin and then look to the Son of God Who gave His life for sins of the world. If you want to know if you are a Christian, see your sins, and look to Christ.