Scripture teaches that Christians are saved by God's grace, which we access by placing our faith in Jesus Christ for the forgiveness of our sins (Rm 3:21-26; Eph 2:8-9). It also teaches that we can persevere in that faith since we are "protected by God's power through faith for a salvation that is ready to be revealed in the last time" (1 Pt 1:5). But can we know with assurance that we truly do belong to the Lord and in the end will be resurrected to eternal life? The answer is yes.
The NT writers were convinced that assurance is available to believers. Paul wrote in Romans 8:1, "No condemnation now exists for those in Christ Jesus," and then concluded that chapter's remarkable discussion with this statement in verses 38-39: "I am persuaded that neither death nor life, nor angels nor rulers, nor things present, nor things to come, nor powers, nor height, nor depth, nor any other created thing will have the power to separate us from the love of God that is in Christ Jesus our Lord!" John was also convinced that believers can have assurance. He wrote, "This is how we are sure that we have come to know Him: by keeping His commands" (1 Jn 2:3). And again: "We know that we have passed from death to life because we love our brothers. The one who does not love remains in death" (1 Jn 3:14).
How can we receive this assurance? Just as medical technicians test vital signs to look for indicators of health, so there are several "vital sign indicators" in Scripture for spiritual health.
1. The Bible says we are to examine ourselves to see whether we are in the faith (1 Co 9:24-27; 2 Co 13:5). There is nothing wrong, and everything right, with a Christian stopping from time to time and asking the question "Am I doing okay, spiritually?" We are not looking for perfection at such times, just signs that God is making a difference.
2. Are we walking in obedience to God? Those who love Him obey Him (1 Jn 2:3). This is an objective test. Again, we are not looking for perfection, since becoming like Christ is a process that lasts a lifetime (Rm 8:29-30; 1 Jn 3:2). The question is, is obedience to Him what I want more than anything else?
3. Do we have a sense that we truly belong to the Lord and He to us? Scripture teaches that if we are Christians, we have the indwelling Holy Spirit (Rm 8:9), a Spirit who "testifies together with our spirit that we are God's children" (Rm 8:16). It is this same Spirit who enables us to cry out, `Abba, Father," to our Father in heaven (Rm 8:15; G14:6).
Scripture gives both objective and subjective vital signs. When it comes down to it, as John Calvin once noted, assurance comes with faith. If we are trusting Jesus alone for salvation, that brings assurance with it.
Extracted from the Apologetics Study Bible.