Many who claim to be Christians do not seem to take sin seriously. They joke about their disobedience and show little concern for living righteously—but sin is what nailed our Lord to the cross. There is nothing more serious than that, and true love does not rejoice in iniquity (1 Corinthians 13:6). Impenitent sin is just as deadly after conversion as it was before conversion (Acts 8:12–24; 1 Corinthians 10:11–12; James 5:19–20).
Jesus, the very one who died to save us, also commands us to take up our cross of obedience and self-denial daily (Luke 9:23). He taught that those who refuse to live obedient lives will never see God. They will see the Lord Jesus when He returns, kneel before the Son of God on the Day of Judgment, and then be cast into eternal Hell. They will never have the privilege of seeing God the Father in all His glory.
God the Father is in Heaven, and only His children who remain pure and holy will go there to see Him and dwell with Him forever:
“Blessed are the pure in heart: for they shall see God” (Matthew 5:8).
“Follow peace with all men, and holiness, without which no man shall see the Lord” (Hebrews 12:14— note that “Lord” can refer to the Father, as in Matthew 1:22; 11:25; Mark 12:29–30; Luke 1:32; 10:21, and Acts 4:24–30).
“No man hath seen God at any time” (1 John 4:12)—and no man ever will, unless he obeys the Gospel and lives a holy life after the pattern of Jesus.
See also: Ex. 33:20; Psa. 24:3–4; Matt. 7:21–23; 25:31–46; Lk. 6:46; Jn. 1:18; 5:37; 6:46; Acts 2:37–42; Rom. 12:1–2; 14:11–12; 1 Cor. 6:9–11; Gal. 5:19–23; Eph. 5:5–6; 1 Thess. 4:13–5:3; 2 Thess. 1:7–9; Titus 1:16; 2:11–14; Heb. 5:9; 10:23–31; 1 Pet. 1:13–22; 2:21–22; 4:17; 1 Jn. 1:6–2:6; Rev. 3:16; 21:27.