There must be confession with the mouth. Have I made it? Have I openly avowed my faith in Jesus as the Savior whom God has raised from the dead, and have I done it in God's way! Let me honestly answer this question.
There must also be belief with the heart. Do I sincerely believe in the risen LORD Jesus? Do I trust in Him as my sole hope of salvation? Is this trust from my heart? Let me answer as before God.
If I can truly claim that I have both confessed Christ and believed in Him, then I am saved. The text does not say it may be so, but it is plain as a pikestaff and clear as the sun in the heavens: "Thou shalt be saved." As a believer and a confessor, I may lay my hand on this promise and plead it before the LORD God at this moment, and throughout life, and in the hour of death, and at the Day of Judgment.
I must be saved from the guilt of sin, the power of sin, the punishment of sin, and ultimately from the very being of sin. God hath said it -- "Thou shalt be saved." I believe it. I shall be saved. I am saved. Glory be to God forever and ever!
Taken from Spurgeon's Faith's Check Book