Of course, a very important part of this life is believing and acting as necessary to attain heavenly salvation. For what good does it do to attain success and happiness in this world, if we are eternally lost? Our temporal life is merely a preparation and prerequisite for our eternal life.
The first requirement for salvation is faith in response to God's grace. We are justified by faith, because faith is the beginning of human salvation. Faith in God the Father, Son, and Holy Spirit as Creator, Redeemer, and Sanctifier is the foundation and root of our justification, without which it is impossible to please God. We must personally accept the redemption Christ won for us on the cross. See John 3:16, 3:34-36, 5:24, 6:28-29, 11:25-27, 20:30-31; Mark 16:16; Acts 16:29-31; Romans 3:22-26, 5:8-11; Ephesians 2:8-10; and 2 Thessalonians 2:13.
However, our faith must be more than mere intellectual belief or acceptance of Church doctrine. We must continually repent of our sins, reject our selfish ways, and seek a deep, prayerful, growing, and trusting relationship with God. According to Vatican II, "By faith, man freely commits his entire self to God, making the full submission of his intellect and will to God." This is conversion.
Conversion is a free and radical offering of one's whole life to God (Mark 8:34-35; Matthew 6:19-21; Matthew 6:24-33; Matthew 10:37-39). Following Jesus demands much more than believing certain truths and doing certain acts of piety (Luke 18:9-14; Luke 14:33). It calls for a deep change, a radical turning about, a total commitment of our lives to Jesus Christ through repentance and obedience of faith (Luke 13:3; 2 Corinthians 5:15; Luke 11:23).
Catholic theology recognizes that conversion is a lifelong process. This conversion process involves moving from self-centeredness and towards doing God's work in the world through service to others. Seeking fulfillment of our own selfish desires (i.e., fun, fame, and fortune) become unimportant.
So, the second requirement for salvation is good works, which flow as the fruit of our faith. Genuine faith requires an active response, which is committed service, ministry, or acts of charity done out of love of God and love of others. St. Paul called this "faith working through love" (Galatians 5:6). See also Matthew 7:21-23, 16:27, 25:31-46; Luke 10:25-28, 18:18-29; John 5:29; Romans 2:6-8; 2 Corinthians 5:10; Ephesians 5:1-5; 1 Peter 1:17; and especially James 2:14-26.
The third requirement for our salvation, Catholics believe, are the sacraments - especially Baptism and Eucharist. Jesus said, "Whoever believes and is baptized will be saved" (Mark 16:16). He told Nicodemus, "Unless a person is born of water and the Spirit, he cannot enter the Kingdom of God" (John 3:5).
Jesus also stated, "Unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. He who eats my flesh and drinks my blood has eternal life, and I will raise him up on the last day." See John 6:53-58. After making this astonishing statement many of Jesus' disciples rejected him and walked away. Remarkably, Jesus did not seek to bring them back by saying they misunderstood his meaning or that he was only speaking symbolically. No, Jesus let them walk away. Clearly, Jesus literally meant what he said. We have been given the precious gift of the Eucharist as spiritual food for our growth in holiness and salvation. As I get older, the spiritual nourishment and strength I receive in the Eucharist has become more meaningful and important in my life.
Just like three legs are needed for a stable tripod, so too faith, good works, and the sacraments are all essential for our salvation. Obviously, when Catholics speak of being saved, they have more in mind than one moment of a person's initial conversion to Christ. Evangelical Christians often believe in one moment of salvation (when you "accept Jesus Christ as your Lord and Savior") and "once saved always saved." Many evangelicals claim they have been "saved." However, Catholic teaching recognizes that we are not the best judge of our own spiritual condition. That is God's call to make, not ours. Jesus told many parables about people who thought they were ready for heaven but were not. See Matthew 7:22-23, 24:45-51, and Mark 13:32-37.
Catholics possess their salvation in confident hope. See Philippians 2:12, 3:12-14; Matthew 7:13-14, 12:31-32; Romans 5:2, 8:24-25; 1 Corinthians 4:3-5, 6:9-10, 9:26-27; and Galatians 5:19-26. While we do not presume to pass a final judgment on ourselves in advance, we do have great confidence that God will give us the grace to persevere in faith and be saved. God will do His part, if we do ours.