This question was put to me recently and here are some thoughts I put together in response.
The answer to this question depends entirely on how you understand salvation. The question has the potential to focus on one’s state rather than one’s relationship to the one who does the saving. Being saved must be related to the one who is the Saviour.
Luke 2:11 For unto you is born this day in the city of David a Saviour, which is Christ the Lord.
John 4:42 And said unto the woman, Now we believe, not because of thy saying: for we have heard him ourselves, and know that this is indeed the Christ, the Saviour of the world.
A better question is:
Do I believe God’s Word and trust in it? What does the Bible tell us?
John 3:14-16 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
John 1:12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
Acts 4:12 Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved.
Act 16:30-31 And brought them out, and said, Sirs, what must I do to be saved? (31) And they said, Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house.
The Bible is clear that if we believe that Jesus is the Son of God and we believe in His name, we shall be saved.
The only requirement is to believe that Jesus is the Son of God and the Saviour of the world. Such a belief will cause us to feel our daily need for Him. The only reason you would truly confess Jesus as your Saviour is because you realise that you need saving from a sinful and selfish life.
The Bible tells us that those who believe in Christ will rejoice and find Him precious:
1 Pet 1:8-9 Whom having not seen, ye love; in whom, though now ye see him not, yet believing, ye rejoice with joy unspeakable and full of glory: (9) Receiving the end of your faith, even the salvation of your souls.
1 Pet 2:7 Unto you therefore which believe he is precious: but unto them which be disobedient, the stone which the builders disallowed, the same is made the head of the corner.
The evidence that we believe is found in the joy we find in Christ our Saviour. When we believe what the Bible says about Him, then we will find Him precious, we will think about Him often and feel a desire to tell others about Him. These things are not done to prove you are saved, but these things come automatically when we believe that Jesus is our Saviour.
So my question would be:
Do you Believe God’s Word about Christ?
If so then we will rejoice in our Salvation. Any doubts about our Salvation is actually disbelief about what the Bible teaches. The Bible is clear that disbelief will cause people to lose their salvation.
John 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
True belief in the Son of God means that we trust in His Word and we believe that He has washed us with His blood and is preparing a place for us. If we doubt this, then we do not truly believe in Him and what He tells us.
This is why Jesus said:
Matt 4:4 But he answered and said, It is written, Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God.
To live by the Word of God is to believe that His Son is our Saviour. To believe in Christ as our Saviour is to rejoice and know He is precious. To be saved is to have confessed our sins and have the calm assurance of the Word of God that we are forgiven for every last one of them and we don't need to worry about those things anymore.