The Bible is clear that if you’re truly saved—if you’ve truly put your trust in Jesus for salvation on the basis of what he did on the cross—then it’s going to show up in your life. Your internal faith will manifest itself in very external ways. You’ll be a different person.

In Matthew 7:15-20, Jesus teaches, “Beware of false prophets, who come to you in sheep's clothing but inwardly are ravenous wolves. You will recognize them by their fruits. Are grapes gathered from thornbushes, or figs from thistles? So, every healthy tree bears good fruit, but the diseased tree bears bad fruit. A healthy tree cannot bear bad fruit, nor can a diseased tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Thus you will recognize them by their fruits.

So Jesus says the way you can tell whether someone’s a false prophet or not is to look at the fruit of their lifestyle. Do they live a godly life? And just like you can use that test to examine prophets or leaders, you can also use that test to examine regular people. If they’re truly saved, if they truly have a relationship with Jesus, there will be good fruit in their lives.

Now, keep in mind that it’s not like we earn salvation by living a godly life. Salvation comes simply by looking to Jesus for rescue, not by trying to be good enough to rescue ourselves. However, even though salvation isn’t attained by a godly life, it is evidenced by a godly life. A godly life may not save you, but it does demonstrate that you have been saved. Just like Jesus said: “every healthy tree bears good fruit, but the diseased tree bears bad fruit.”

Let’s say my wife asks me to plant an apple tree in the front yard. Now, we already have a tree in our front yard, but let’s say she wants me to plant another tree because she wants to eat fresh apples. So I go out and make the purchase, and I plant that tree in the front yard just like I’m instructed. And it takes a few years, but the tree eventually starts to produce fruit. Only, for some reason, it doesn’t seem to be producing apples; it seems like it’s producing oranges.

So my wife asks me, “Josh, I thought we agreed to get an apple tree and you said you had purchased an apple tree. What happened?” And I tell her, “Oh, I did purchase an apple tree. It just happens to be producing oranges at the moment.” How do you think my wife will respond to that? She’ll probably ask me, “What the heck are you talking about? Apple trees don’t produce oranges. Orange trees produce oranges. If that tree were truly an apple tree, it would be producing apples.”

And that’s the same thing Jesus is saying here. We may not be able to know with 100% certainty what’s in a person’s heart since only God can see inside people’s hearts. But according to Jesus here in Matthew 7, we can have some idea of whether someone’s genuinely saved or not by observing how they live their life—by looking at the fruit they produce. And of course, we never want to do that with a judgmental attitude, but the fact remains genuine salvation shows up in your life.

1 John gives us several marks of a genuine believer (these have helpfully been brought to my attention by Paul Washer). By looking for these things in your life, you can have a relatively good idea of whether you’ve truly been saved.

The first mark is walking in the light, and that’s found in 1 John 1:5-7: “This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. If we say we have fellowship with him [if we say we’re saved] while we walk in darkness, we lie and do not practice the truth. But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.” So are you walking in the light? Are you trying to live the way God has instructed you to live?

The second mark is confessing sin. 1 John 1:8-10: “If we say we have no sin, we deceive ourselves, and the truth is not in us [we’re not saved]. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say we have not sinned, we make him a liar, and his word is not in us.” So do you confess your sins to God and try to turn away from those sins, or do you tolerate areas of sin in your life and pretend they’re not even there? A true Christian is sensitive to the sin in their life and walks in regular repentance.

Then the third mark is very similar: obeying the commands of God. 1 John 2:3-4: “And by this we know that we have come to know him [that we’re truly saved], if we keep his commandments. Whoever says ‘I know him’ but does not keep his commandments is a liar, and the truth is not in him.” So do you have a desire to obey God’s commands? We’re not talking about perfection here; nobody’s able to obey God perfectly. But are you at least striving to obey God?

The fourth mark is genuinely loving other believers. 1 John 2:9-11: “Whoever says he is in the light and hates his brother is still in darkness [he’s not saved]. Whoever loves his brother abides in the light, and in him there is no cause for stumbling. But whoever hates his brother is in the darkness and walks in the darkness, and does not know where he is going, because the darkness has blinded his eyes.” So do you love other Christians? Do you have some desire to be around them and gather with them on Sundays? Do you have some inclination to serve them and put their welfare above your own? Do you try your best to overlook any instances in which they rub you the wrong way rather than stir up needless division in the church?

And finally, the fifth mark of a true Christian is that they’re not in love with worldly things. 1 John 2:15: “Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world—the desires of the flesh and the desires of the eyes and pride of life—is not from the Father but is from the world.” So is your heart more inclined toward the things of this world—earthly joys and treasures—or is it more inclined toward God?

Those are the five marks we get from 1 John. Someone who’s truly saved will be walking in the light, confessing sin, obeying God’s commands, loving other believers, and not loving worldly things.

Of course, they’re not going to be perfect. They’re going to stumble and fall a lot—kind of like my one-year-old who’s just learning to walk. He’s a wobbly little guy, and he falls a lot. But he has that desire to walk, and he tries his best. And in the same way, a true Christian won’t be perfect, but they will be different.