The easiest way for a person to have a false assurance of salvation is to have a false doctrine or understanding of salvation.

If a person holds onto a false doctrine, their assurance will be unstable since it isn’t grounded in the truth of scripture.

One example of a false doctrine of salvation is “universalism”, which teaches that everyone is saved regardless of their religious beliefs (even if they reject Christ). Such people are sadly living with false hope and assurance due to their bad doctrine.

Another way people can falsely assure themselves of salvation is by believing that by “living a good life” they will be saved. This idea that you can satisfy the demands of a Holy God by just living a good life is unbiblical and delusional.

But also could someone who believes in a sound doctrine of salvation still have a false assurance of salvation? It could be possible (though unlikely) for someone who believes in the true gospel to lack true saving faith.

It is for this reason that the Bible urges all Christians to examine their hearts to determine whether they have true faith in Christ.

2 Corinthians 13:5 (NKJV)

Examine yourselves as to whether you are in the faith. Test yourselves. Do you not know yourselves, that Jesus Christ is in you?—unless indeed you are disqualified

It is imperative to test our hearts to determine whether we have genuine love for the Biblical Christ because such love is impossible without God’s regenerative work.

A further way to check the authenticity of our assurance  is to examine the fruit of our faith. By no means are we saying that one must produce a perfect fruit to prove our faith as credible, but there should be some evidence of it.

If there is no fruit, then neither is there genuine faith. When true “saving faith” is found, the “fruit” of that faith is also found.