You'll hear Baptist preachers say "Do you know you're saved without a shadow of a doubt?" How can you answer that question without understanding doubt and its source?
Doubt is disbelief. Doubt is not trusting. A doubter in the immediate context is a person whose belief is not firm enough in Christ to trust Him. Is Jesus who he says he is? Does Jesus live today? Will I really have eternal life?
When Peter was walking on the water with Jesus his faith wavered and he began to sink. Matthew 14:31 "And immediately Jesus stretched forth his hand, and caught him, and said unto him, O thou of little faith, wherefore didst thou doubt?"
"Doubt" is "wavering faith". Peter didn't abandon Jesus, he just questioned Jesus' power and identity. He knew Jesus, he believed in Jesus and he accepted Jesus, but something in his heart said "I value my life more than taking a chance on this man Jesus!" Doubt is then the inverse of faith. If Peter had the unwavering faith he would have continued his walk on the water rather than sinking in fear. Note that he had the faith to step out, but not enough faith to continue his walk.
Walking on water really happened! There were witnesses to it and it was written about. Why do you doubt this event? Why do you doubt Jesus?
Now let's go back to Peter. He had faith. He also had doubt. Did he go from saved to unsaved? No! He was still a Christian when he was having doubt. You see, man is always weighing everything: There is pleasure (or safety which is self-gratification) in what I'm doing (or not doing). Is it worth it to lose the opportunity for pleasure (or safety) to follow Jesus? Conversely, if I follow Jesus I miss out on worldly pleasures. Is it worth it? (Even if I believe in Jesus?)
We all waver in our faith as we walk in Christ. We may be on the peak if we're walking on the water with Jesus, but in the swirl of doubt if we feel life sucking is down to the depths. Most of the time we waver only enough that prayer and scripture throws us a life-jacket, but at other times we grab an anchor. We cling to the material things of life which sink us while abandoning the life-preserver of Scripture. Yes, "Hope Floats!"
My contention is that the statement "Are you saved beyound a shadow of a doubt?" puts a Christian in a precarious position: Does he lie and say "yes" or does he just confess and say "No, Jesus, at times I do doubt!" An addenda to this confession is "Lord, remove my doubt." If you doubt at times you're still a Christian, but if you live in constant doubt, self-examination and the sinner's prayer is the answer! Peter did doubt at this time. Something flashed in his mind and he questioned his faith in Jesus. He began to sink, but he didn't drown. His faith kept him afloat! Jesus' salvation is excellent on the mountaintop and in the whirlpool!
Who is the author of doubt? Satan. That's his job. That's his chosen profession! His entire existence is to undermine Jesus. His tools are lies, distortions, half-truths, deceit, temptation and tricky Christianity. Of all those "tricks" in Christianity are the hardest to discern!
Satan deceives even the elect (the saved) by putting just enough of "God" and "Jesus" into his tool that the Christian (as well as sinners) believe the activity is "good". Liberal churches are dens of iniquity. They're tools of Satan and damn those who attend and believe the tricks of Satan. What are some of the tricks?
1) Scripture is not divinely inspired.
2) Jesus was just a just good teacher.
3) Sin is abstract. Good and evil is not absolute. Truth has shades of gray.
4) A good God can't let sinners go to hell.
5) If you're good, God will take you to heaven.
6) You don't have to live a Christian life. You'll be saved in your apostasy.
7) Tolerance of sin is the graceful thing to do.
8) You shouldn't talk to others about sin because you shouldn't judge.
9) God provides wealth and health to those who believe.
10) Science is fact and Scripture only belief.
11) God must do things according to the box we put Him in.
12) Satan and Hell don't exist.
13)All life, the gift of God, is not precious. It must be terminated at times for the welfare of the others.
14) Sexual deviancies are not behaviors. There are those are born that way.
15) We can participate in worship of other gods because all gods are really the same God.
The list goes on and on. If you're going to a church which teaches and/or allows a "type of Christianity" and not the full-fledged thing, then you're drowning. By calling only on Jesus of Scripture will you be lifted from the miry waters and glide across the temptuous seas. Let the real Jesus, the Truth, be your pilot. Don't listen to the muntineers who care not whether you sink or swim!