What is the faith that will bring us salvation? Is it enough to believe in Jesus Christ, the Son of God?
St John Chrysostom writes
He that believes in the Son has everlasting life." Is it enough, then, to believe in the Son,' someone will say, 'in order to have everlasting life?' By no means! Listen to Christ declare this himself when he says, 'Not everyone who says to me, "Lord! Lord!" shall enter into the kingdom of heaven'; and the blasphemy against the Spirit is alone sufficient to cast him into hell. But why should I speak of a part of our teaching? For if a man believe rightly in the Father and in the Son and in the Holy Spirit, but does not live rightly, his faith will avail him nothing toward salvation (Homilies on the Gospel of John 31:1[circa A.D. 391]).Jesus himself tells us that mere belief is not sufficient. The Lord Himself said,
“Not everyone who says to Me, `Lord, Lord,' shall enter the kingdom of heaven” (Matt 7:21). The Lord continues “Many will say to Me in that day, `Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?' And then I will declare to them, `I never knew you; depart from Me, you who practice lawlessness!' (Matt.7:22-23).Faith is not simply a belief but also a life. You can test it by its fruits in your life... as the Lord said
“You will know them by their fruits….every good tree bears good fruit, but a bad tree bears bad fruit. Therefore by their fruits you will know them” (Matt. 7:16-20).
John the evangelist teaches us
“Now by this we know that we know Him” how? “If we keep His commandments. He who says, "I know Him," and does not keep His commandments, is a liar, and the truth is not in him ” (1 John 2:3-4).
Faith is tested through a life of obedience to God's commandments, and he who does not have this obedience is not considered a believer of Truth, and can not claim to know God.
The intellect may guide you to the beginning of the way but faith continues with you on the way to the end. Faith does not contradict the intellect, but leads it to a higher level the mind alone cannot reach.... The mind can bring you to know God and some of His qualities but of faith, “God has revealed… to us through His Spirit.” (1 Cor. 2:10). God shows Himself to the believer to what they can bear to comprehend.Faith is something that is always underdevelopment and constantly being tested. We should never assume we have sufficient faith. It demands the perfect love of God and others. Its limits are discovered in our tendencies for sinfulness and our fears. The best work of the devil is to convince someone that they are saved but their declaration of faith. This is only a starting point along the path to salvation. Only God grants us the grace of salvation.
Reference: Life of Faith, Pope Shenouda III of the Coptic Church