Many bible believers are obsessed with looking inwardly to determine if they have the Holy Spirit, usually on a quest to determine whether or not they are saved. Interestingly these people believe the bible enough to go on this quest, but then are worried they aren't measuring up which begins the obsessive self examination in search for evidence of life.
The problem is the moment you start looking within you've already been duped. It's not that we aren't to examine ourselves to see if we're in the faith (2 Cor. 13:5), the problem is we're searching in all the wrong areas. Looking within for assurance of salvation is like a captain of a ship putting it's anchor on the bow of the boat expecting it to hold them steady. Then when it doesn't he moves it to the stern, and when that doesn't work, he puts it in the crew quarters, then in the kitchen. When that fails, in desperation he begins asking his crew what part of the ship he should put the anchor.
Unfortunately the captain is surrounded by a crew who themselves don't know where the anchor goes so they all suggest different spots on the ship and go through some pretty strenuous ways of securing the anchor in some pretty absurd places on the ship. They take the sails down and hang the anchor up in it's place, when that doesn't work they begin throwing cargo overboard thinking if they just lighten the load then the anchor won't have to work so hard at keeping the ship secure. All of them gather around the anchor, each one making confident assertions about what they think should be done, and nobody is listening to the guy scrubbing the deck who quietly states "you should throw it overboard".
"Throw it overboard, that's absurd!" Because even though you know something needs to be done, you're sure that's not it. "Throw it overboard" you muffle to yourself as you're thumbing through the ship's owner's manual, "that's ridiculous" you conclude. Then you get to the page on "how to use the anchor" and read "release anchor into Ocean" and you pause for a moment and think maybe there's some validity to what the scrawney deck hand was saying, but you consider his credentials, after all he's merely a deck hand, and you reason to yourself "it took 10 guys to lift this anchor, if we throw it overboard it'll drag the entire ship down!" You know the anchor can keep the ship from drifting but because of it's importance to you the last thing you're willing to do is throw it overboard. In frustration you toss the manual on the floor and return to the crew to troubleshoot how you're going to keep this ship from drifting trying all the same things again, sure that you missed something.
You're desperate to not drift and be lost at sea, but unwilling to consider options outside yourself, and therefore you have not a solution to the problem at hand. You're convinced there's a problem, and that the solution must be within your grasp. Yet faith is "proof of things not seen". (Heb. 11:1b)
Another analogy may be like a very thirsty man who stares inside an empty bucket from the well afraid if he lowers it he won't be able to look inside to see if there's any water.
The enemy loves to get us looking within. This was the same temptation with Jesus when Satan's opening lines started with "If you are the Son of God..." (Matt. 4:3, 6). The enemy loves convincing us there's a problem within and then convincing us the solution must be within our realm of control.
It's not.
I love Paul's example. In 1 Corinthians 4:3-4 he states that for another to examine him is insignificant, for he doesn't even examine himself. Therefore we too should not bank on what others say about us, nor obsessively look inwardly but rather entrusts ourselves to God and trust Him with our well-being. (Isa. 53:5).
Scripture defines faith as "proof of things not seen" (Heb. 11:1b) and it is faith which puts out the fiery arrows of the evil one (Eph. 6:16). You need to be deliberate to drop the anchor into the ocean floor, you need to be deliberate to lower the bucket into the well. Don't count on your heart to preach to you, it's "deceitful" and "desperately wicked" (Jer. 17:9) and it wants bad things (Gal. 5:16-17). Neither will life be found even in scripture (John 5:39). The Ocean floor is Jesus who is the "Anchor of our souls". And Jesus is the "living water" in which we must draw from (John 4:10) and that alone will satisfy what you're looking for.
When the thought hits "how do I know if I'm saved" do not look inwardly but look outwardly. As Hebrews 12:2 states "fix your eyes on Jesus, the pioneer and perfecter of faith!" Answer the question with a question! When the question arises "how do I know if I'm saved?" Answer it with another question "Was Jesus successful on the cross?". Judge your salvation based on the life of Jesus, His accomplishments, His performance. Do not ask if you are worthy to enter the kingdom, ask if Jesus is worthy to enter the kingdom, after all we're clothed in His righteousness. If your defense comes from within it can be challenged, but if your defense for entry into the Kingdom is Jesus, then the accuser is forced to reckon with Him and His perfect fulfillment of the law, and His sacrificial atoning death on the cross, and that is not a battle the accuser can win.
Your entry into heaven is completely contingent on Jesus Christ therefore meditate no longer on if you're worthy, but dwell on just how worthy He is to enter because by His doing we are not judged by our performance, we're judged by His performance. Therefore the accuser has to find cause with Him if he is going to have grounds to disqualify us.
The Apostle Paul didn't even examine Himself, it would be prudent if we too entrusted our examination to the Lord as well. (1 Cor. 4:3-4).
"I will not say much more to you, for the prince of this world is coming. He has no hold over me" - Jesus (John 14:30).