1) Doubting your salvation. If you are doubting your own salvation this can actually be a sign that you are a believer, or at the very least, on a sincere path to discover God. The enemy is not in the business of causing unbelievers to think about the topic of salvation, and he is definitely not wanting you to start applying your doubts to this situation. To reiterate, this is not a fool-proof test, but in my experience this mostly applies to believers who are struggling in challenging seasons of their life.
2) When is the last time God has spoken to you? I've found that this is a good indicator if you are a believer because of your decision to meditate on what God is saying to you through His Word, His People, and His Church. If you are not reading your Bible, meeting with a small group of dedicated believers, or attending a Bible-believing Church, I think you are at best far away from God and at the worst, not a child of God.
3) Do you pray for others to know Christ personally? If you are a believer, you will rejoice when confronted with news of someone's decision to follow Christ, and will pray for those in your life that you know aren't living a life of faith.
4) Are their fruits of God's Spirit in your life? Do you see areas of your life where God is working, in particular character issues and/or patterns of sin that have held you captive in the past? If you are praying and asking God to help you live a better life so that you can influence and grow His Kingdom that is a good indicator that you are a child of God's.
5) Finally, do you obey God? Jesus said, "If you love me you will obey me." Obedience and seeking to please God is a strong marker that God is working in your life as one of His children. And another characteristic of a child of God is someone who is at odds with this world and its values.
Curious to see where you stand? Post something about Jesus Christ being the only way to salvation and then step back and observe the fireworks. If you love this world, and you are seeking to fill your days with the pleasures of this reality, I encourage you to do a deep dive into the desires of your heart. Here is an insightful quote to illustrate this point, "The early Christians were not fed to wild beasts because they thought Jesus was a helpful life coach or role model." - Michael Horton
Now let's segue to 1 John which is a great book of the Bible to recommend for those who might be doubting their salvation.
1. 1 John 1:5-7 (Walking in the Light) "This is the message which we have heard from Him and declare to you, that God is light and in Him is no darkness at all. If we say that we have fellowship with Him, and 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 Christ His Son cleanses us from all sin."
2. 1 John 1:8-10 (Confession of Sin) "If we say that we have no sin, we deceive ourselves, and the truth is not in us. 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 that we have not sinned, we make Him a liar, and His word is not in us."
3. 1 John 2:3-4 (Obedience) "Now by this we know that we know Him, if we keep His commandments. He who says, "I know Him," and does not keep His commandments, is a liar, and the truth is not in him."
4. 1 John 2:9-11 (Love for the Brethren) "He who says he is in the light, and hates his brother, is in darkness until now. He who loves his brother abides in the light, and there is no cause for stumbling in him. But he who hates his brother is in darkness and walks in darkness, and does not know where he is going, because the darkness has blinded his eyes."
5. 1 John 2:15-17 (Hatred for the World) "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 lust of the flesh, the lust of the eyes, and the pride of life--is not of the Father but is of the world. And the world is passing away, and the lust of it; but he who does the will of God abides forever."
6. 1 John 2:24-25 (Perseverance in Doctrine) "Therefore let that abide in you which you heard from the beginning. If what you heard from the beginning abides in you, you also will abide in the Son and in the Father. And this is the promise that He has promised us--eternal life."
7. 1 John 3:10 (Righteousness) "In this the children of God and the children of the devil are manifest: Whoever does not practice righteousness is not of God, nor is he who does not love his brother. For this is the message that you heard from the beginning, that we should love one another."
8. 1 John 4:13 (Spirit's Testimony) "By this we know that we abide in Him, and He in us, because He has given us of His Spirit."
