Are Catholics Christian?

Yes, Catholics are Christians

One becomes Christ's disciple through baptism in the name of the Father, Son and Holy Spirit (Matthew 28:19), which requires belief in the Trinity and in the Son sent as Savior (John 3:16-17). Catholics profess the Nicene Creed, from Nicaea (325), a faithful development of the Apostles' Creed rooted in the apostles' teaching (Acts 2:42; Matthew 28:20). The question arises because some think Catholics worship something other than Jesus in the Mass.

Catholics are Christians, but not all Christians are Catholic. Some Eastern Christians separated while keeping the seven sacraments; from the 1500s, with Luther, many more broke away. Using "Christian" only for Protestants is misleading.

The words

Followers of Jesus were first called Christians at Antioch (Acts 11:26). Catholics believe in the one true Christ (John 14:6), the Son who became flesh (John 1:1-3, 14), born of the Virgin, crucified, risen, ascended, who sent the Spirit and will come to judge. "Catholic" (katholikos) means "universal," fitting the mission to all nations (Matthew 28:18); its oldest surviving use is by Ignatius of Antioch around 110. Believing the Church one, holy, catholic and apostolic is inseparable from belief in the Trinity (CCC 750).

Who founded the Church?

Jesus founded a visible Church on the apostles (Ephesians 2:19-20), giving them authority to baptize, forgive sins (John 20:21-23) and offer his sacrifice in memory of him (Luke 22:19-20). He gave Peter and his successors primacy and the keys (Matthew 16:18-19), promised the Spirit would lead them into all truth (John 16:13), and provided for successors (see Acts 1:15-26; Matthew 28:20).

Salvation

Some Protestants define being Christian by a personal declaration of faith that gives eternal security, and infer that Catholics believe in salvation by works. That is wrong. Salvation is a free gift made possible by Christ's sacrifice: by grace we have been saved through faith, and this is not our own doing (Ephesians 2:8-9). Faith is necessary for salvation (CCC 161), but not faith alone apart from living it out. We must persevere (Matthew 7:21-23; 10:22), abiding in God's love (John 15:5-6, 10; James 2:14-17); mortal sin forfeits sanctifying grace (see 1 Corinthians 6:9-10; Galatians 5:19-21; CCC 1854-1864), requiring repentance.

Belief in Jesus

Catholics believe Jesus is the Son of God made man, fully God and fully man, born of the Virgin Mary, crucified, died and buried, risen on the third day and ascended, the author of salvation who will come to judge. At Mass, the source and summit of Christian life (CCC 1324), his one sacrifice is offered anew as he commanded (Luke 22:19-20), and we receive him to have eternal life (John 6:53-58). Catholicism is the fullness of Christianity.

The Nicene Creed

Catholics profess it every Sunday:

I believe in one God, the Father almighty, maker of heaven and earth, of all things visible and invisible. I believe in one Lord Jesus Christ, the Only Begotten Son of God, born of the Father before all ages. God from God, Light from Light, true God from true God, begotten, not made, consubstantial with the Father; through him all things were made. For us men and for our salvation he came down from heaven, and by the Holy Spirit was incarnate of the Virgin Mary, and became man. For our sake he was crucified under Pontius Pilate, he suffered death and was buried, and rose again on the third day in accordance with the Scriptures. He ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead and his kingdom will have no end. I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son, who with the Father and the Son is adored and glorified, who has spoken through the prophets. I believe in one, holy, catholic and apostolic Church. I confess one Baptism for the forgiveness of sins and I look forward to the resurrection of the dead and the life of the world to come. Amen.

The real difference

The difference is between the one Church Christ founded and groups that later split from it. Full communion includes charity and the visible bonds of one apostolic faith, common worship and sacraments, and apostolic succession (CCC 815). Catholics invite separated brethren to full communion out of obedience to Christ's prayer for unity (John 17:20-23) and desire that they know the truth that sets free (John 8:31-32).

"Roman" Catholic

"Roman" refers to Rome, where Peter and Paul were martyred and the Holy See is located. After the Reformation, the label was used to deny the Church's universality. It can properly refer to the Latin Rite, and Eastern Catholics are in communion with Rome, but used pejoratively it denies the Church's four marks (see CCC 811-812). A personal relationship with Christ is crucial, rightly ordered within the one Church he founded and sustains.