Faith in Christianity in the context of "Christianity in the 1st century"

In Christianity, a martyr is a person who was killed for their testimony for Jesus or faith in Jesus. In the years of the early church, stories depict this often occurring through death by sawing, stoning, crucifixion, burning at the stake, or other forms of torture and capital punishment. The word martyr comes from the Koine word μάρτυς, mártys, which means "witness" or "testimony".

At first, the term applied to the Apostles. Once Christians started to undergo persecution, the term came to be applied to those who suffered hardships for their faith. Finally, it was restricted to those who had been killed for their faith. The early Christian period before Constantine I was the "Age of Martyrs". "Early Christians venerated martyrs as powerful intercessors, and their utterances were treasured as inspired by the Holy Spirit."

A church service (or a worship service) is a formalized period of Christian communal worship, often held in a church building. Most Christian denominations hold church services on the Lord's Day (offering Sunday morning and Sunday evening services); a number of traditions have mid-week services, while some traditions worship on a Saturday. In some Christian denominations, church services are held daily, with these including those in which the seven canonical hours are prayed, as well as the offering of the Mass, among other forms of worship. In addition to this, many Christians attend services on holy days such as Christmas, Ash Wednesday, Good Friday, Ascension Thursday, among others depending on the Christian denomination.

The church service is the gathering together of Christians to be taught the "Word of God" (the Christian Bible) and encouraged in their faith. Technically, the church in "church service" refers to the gathering of the faithful rather than to the physical place in which it takes place. In most Christian traditions services are presided over by clergy wherever possible, but some traditions utilize lay preachers. Styles of service vary greatly, from the Catholic, Lutheran, Eastern Orthodox, Oriental Orthodox, Reformed (Continental Reformed, Presbyterian and Congregationalist) and Anglican traditions of liturgical worship to informal worship characterized by certain free church traditions, common among Methodists and Baptists, that often combine worship with teaching for the believers, which may also have an evangelistic component appealing to backsliders and the non-Christians in the congregation (cf. altar call). Quakers and some other groups have no formal outline to their services, but allow the worship to develop as the participants present feel moved.

Sola scriptura (Latin for 'by scripture alone') is a Christian theological doctrine held by most Protestant Christian denominations, in particular the Lutheran and Reformed traditions, that posits the Bible as the sole infallible source of authority for Christian faith and practice. Sola scriptura is a formal principle of many Protestant Christian denominations, and one of the five solae theorized in the early 20th Century in attempts to characterize common ground in disparate Protestant theologies.

The Catholic Church considers it heresy and generally the Orthodox churches consider it to be contrary to the phronema of the Church. While the scriptures' meaning is mediated through many kinds of subordinate authority—such as the ordinary teaching offices of a church, the ecumenical creeds, councils of the Catholic Church, or even personal special revelation—sola scriptura in contrast rejects any infallible authority other than the Bible.

Presbyterianism (pres-bə-TE-ree-a-nizm) is a historically Reformed Protestant tradition named after its form of church government by representative assemblies of elders, known as "presbyters". Though other Reformed churches are structurally similar, the word Presbyterian is applied to churches that trace their roots to the Church of Scotland or to English Dissenter groups that were formed during the English Civil War, 1642 to 1651.

Presbyterian theology typically emphasises the sovereignty of God, the authority of the Scriptures, and the necessity of grace through faith in Christ. Scotland ensured Presbyterian church government in the 1707 Acts of Union, which created the Kingdom of Great Britain. In fact, most Presbyterians in England have a Scottish connection. The Presbyterian denomination was also taken to North America, Australia, and New Zealand, mostly by Scots and Scots-Irish immigrants. Scotland's Presbyterian denominations hold to the Reformed theology of John Calvin and his immediate successors, although there is a range of theological views within contemporary Presbyterianism. Local congregations of churches that use Presbyterian polity are governed by sessions made up of representatives of the congregation (elders), a conciliar approach as with other levels of decision-making (presbytery, synod, and general assembly). There are roughly 75 million Presbyterians in the world.

Sola fide, meaning "faith alone," is a Christian doctrine that teaches sinners are forgiven and declared “not guilty” through faith—apart from good works or religious deeds. Protestants traditionally believe that this doctrine of salvation is the cornerstone of Christianity, the very teaching "upon which the church stands or falls".

In classical Protestant theologies, works are the natural evidence of faith, but they do not determine salvation. Confessional Lutheranism sees justification as free forgiveness, received only through faith. Without faith, God's forgiveness is rejected and its benefits are forfeited. Methodism affirms the doctrine of justification by faith alone, but holds that holy living with the goal of Christian perfection (entire sanctification) is essential for salvation; maintenance of sanctification is contingent on continual faith in and obedience to God.

Repentance (a term related to Greek: μετάνοια, romanized: metanoia), in Christianity, refers to being sorrowful for having committed sin and then turning away from sin toward a life of holiness.

In certain Christian traditions, such as Catholic theology, Lutheran theology, Orthodox theology and Anglican theology, repentance plays a key role in confession and absolution. It can specifically refer to a stage in Christian salvation in which an individual gains awareness of God's standard, acknowledges their past or present wrongdoings, and deliberately turns away from sin toward God; its numeration as a stage in the ordo salutis varies with the Christian denomination, with the Reformed theological tradition arguing it occurs after faith. Christian denominations that adhere to the liturgical kalendar, such as Catholicism, Lutheranism, Moravianism and Anglicanism, focus on repentance during the season of Lent, while emphasizing its importance in the life of the believer throughout the year.