Repentance is often referred to as the flip side of faith, like a coin, heads and tales, faith and repentance. However, repentance is not synonymous with faith. They are related, but not the same. In John's account of the life of Jesus, he uses several words such as, "receive, look, hear, enter, drink, and come, which are synonymous with faith. But he never uses the word "repentance" in his account, not once.
Most define "repentance" in two ways: a 'change of mind" and/or a "change of direction". Some say that a "change of mind" in addition to faith in Christ, is all that is necessary for salvation. Others say that it must also include a "change of direction" that is, "a turning from your all sins" which is the evidence of one's salvation. Many say repentance is an element that is included within the definition of faith.
A "change of mind" repentance could simply be the consequence of believing in Jesus for eternal salvation, not the cause. A "change of mind" is the consequence or the result of believing. A "change of mind" does not necessarily cause the unbeliever to believe. But when the unbeliever believes, he has as a result "changed his mind".
For example, the rich young ruler believed that he could be saved by keeping the Law. If he had believed in Christ alone for eternal life, one could infer that he would have "changed his mind", and "repented", even though John does not say so.
Another example: an unbeliever is invited to come to church or an evangelistic meeting to hear the free grace gospel, which he at first declines. Later, he "changes his mind" and goes, hears, and believes the message of life and is saved. Here again, "changing his mind" is related to, but not synonymous with believing. He could have still gone, heard, and not believed. Changing one's mind about God and spiritual things may possibly lead to an individual's openness to hearing and believing the FFG, resulting in eternal salvation.
A "change of direction" repentance "change in behavior" or "turning from sin", is what is necessary to avoid the natural consequences of sin which is the temporal wrath of God on our lives. Faith alone will not help you. This is true for both unbelievers and believers. Anyone who lives "by the flesh" will reap the natural consequences of corruption. No one is immune to this undeniable truth. However, anyone who repents can avoid these consequences and be saved from the wrath of God.
No one can or will actually repent from all of their sins, no matter how much they fervently promise to do so. Nowhere in Scripture does it say that a sinner needs to repent of all of their sins in order to receive everlasting life. If this were true, then no one could be saved. No, what a sinner needs is life received by faith in Christ who died to set us free from the eternal penalty of sin.
If a saved sinner wanders away from the Lord and walks with the world, he is in serious danger of severe discipline from the Lord. The wrath of God is revealed against all ungodliness of men regardless of their eternal destiny. God's wrath can take on many forms--sickness, economic ruin, mental stress, even physical death. To avoid God's wrath the sinner must repent of his sins and begin walking in His Spirit. Free Grace Theology does teach that there is a call to repentance, just not a call to repentance accompanied by an element of faith for everlasting life.
FYI, The last command given to the church is not, "Go ye", but "repent ye"!