“The Spirit Himself testifies with our spirit that we are children of God . . .” (Rom. 8:16). “By this the children of God and the children of the devil are obvious: anyone who does not practice righteousness is not of God . . .” (1 John 3:10)
Answering the question, “Are you a Christian?” and answering the question, “Are you sure you’re a Christian?” can evoke two different responses. Many a child of God has struggled with the latter, while many a hypocrite should have struggled with the former (Matt. 7:22-23). So how does a person really know if he is one of God’s elect? A few observations on possessing biblical assurance:
First, assurance is not positive thinking, the eternal security of the believer, once saved always saved, or faith itself. It’s not how hard we believe ourselves saved based on some past religious act or even on the objective work of Christ by itself. Assurance is simply the personal confidence that I’m a child of God. Being assured in what Christ has done is different than being assured I’m included in that work Christ has done. One grows out of the other, but they’re not the same.
Second, assurance is a personal gift as well as a common fruit. The Father can tell His child at any time, under any circumstance, that he is bought by Christ’s blood (Lk. 10:20). It doesn’t depend on the child’s performance -- and many times is given in spite of it (Rom. 9:25-26). On the other hand, assurance is a process borne out of much perseverance (2 Pet. 1:5-11), overcoming (Rev. 3:5), and proven character (Rom. 5:4). It comes after years of running a race and fighting a fight (2 Tim. 1:12; 4:7-8).
Third, assurance is optional, as well as necessary. It’s optional in that salvation depends on knowing what to believe, not on knowing if I’m believing it. One man’s confidence he’s a Christian is another man’s struggle -- and God is the savior and determiner of both. God has his sanctification purposes in withholding it from some and lavishing it on others. Our confidence should be in our Father’s good distributing hand rather than idolizing the mental comfort of possessing that gift. Better to walk in darkness and have no light (Isa. 50:10-11) than to have all kinds of light and crawl (Heb. 5:11ff.). No man will see the Lord without holiness (Heb. 12:14), but many will see Him without assurance.
But assurance is also necessary -- not for salvation, but for faith. All faith possesses a measure of assurance in what God has promised (Heb. 11:1). It’s an objective confidence outside of ourselves, in someone else. Questioning my performance isn’t the same as questioning God’s (Heb. 6:11-14).
It’s a good thing to know you’re an heir of God, written in the will, an inheritor of eternal things. What a blessed gift! But avoid two errors: Be careful who you assure they’re a Christian, as it’s not yours to give. Better to say we have great encouragement we’re one of His as we press on to maturity. And second, don’t be afraid to take assurance away from those who falsely trust in it without fruit (Ezek. 13:22; Jam. 5:19). Wait on the first, don’t wait on the second.