Salvation is with assurance.
It is God’s will that you should know you are his. When people ask ‘Are you saved?’ he does not expect his children to answer, ‘I hope so’, ‘I’m trying’ or I’d like to think I am.’ He wants us to be sure of it, not with arrogance but with faith; not sure of ourselves, but sure of him and his promises.
This assurance comes through his word of promise at first, but it also, and perhaps more profoundly, comes from our consciences, as they begin to assure us that at last we are free of this destructive thing called sin, that there is a charge in our manner of life, and that we are children of God. Above all God wants to plant in our hearts the power of his Holy Spirit. It is by this gift that his children can call him ‘Father.’ After all, it is the birthright of children, and he intends it for us.
There are people who believe in God and trust in Christ. Through faith they have received the grace of salvation. But they still lack assurance. They worry and fret about their standing before God, and so their testimony is weakened. For such people the great need is to ask God to take them one step further, to pour his Holy Spirit into their hearts to bear witness to the fact that they are children of God, bound for heaven.
Assurance (Necessary for Salvation)
And thy life shall hang in doubt before thee; and thou shalt fear day and night, and shalt have none assurance of thy life:
And the work of righteousness shall be peace; and the effect of righteousness quietness and assurance for ever.
Because he hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead.
That their hearts might be comforted, being knit together in love, and unto all riches of the full assurance of understanding, to the acknowledgement of the mystery of God, and of the Father, and of Christ;
1 Thessalonians 1:5
For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
And we desire that every one of you do shew the same diligence to the full assurance of hope unto the end:
Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.