When sharing the Catholic faith with other Christians, it is critical that we speak their “language” – Sacred Scripture.

Every verse of Scripture supports Catholic teaching, but some are particularly clear and powerful. Here are 10 key Bible verses that every Catholic should be able to knowledgeably share, to help work toward the “perfect” Christian unity that Jesus prayed for in John 17 below.

1) Perfect Christian Unity: How the World Will Know God Sent Jesus

John 17:17-23: “I pray … that they may be one, as we are one, I in them and you in me, that they may be brought to perfection as one, that the world may know that you sent me”.

There are few things more important than Christian unity. The last thing Jesus prays for before being arrested is “perfect” unity in his followers. Why? Jesus tells us: “that the world may believe that you sent me … and that you loved them.” This is the heart of evangelization, and Christian unity is at the centre of it.

This is not piecemeal unity, with thousands of different Christian denominations teaching different things on very important topics like divorce/remarriage, contraception, abortion, homosexuality, baptism, or the Eucharist. Jesus twice calls it “perfect” unity.

2) Jesus Builds His Church on Peter and It Will Never Fall

Matthew 16:16-19: “Thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven.”

Jesus didn’t first write the Bible, he first came to found his Church. But he didn’t found thousands of different denominations. He founded one Church. It is a fact of history that this Church is the Catholic Church.

Some claim that Jesus’ Church apostatized at some point. But this simply isn’t possible. Jesus is the wisest of builders. When he builds his house (and St. Paul tells us that “the house of God” is the church in 1 Timothy 3:15), it will never fall, no matter the storms (Mt 7:24-25). He builds his house – his church – on Peter, Petros (Greek for rock), and promises “the gates of hell shall not prevail against it.”

3) We Do Not Follow the Bible Alone (Sola Scriptura)

2 Thessalonians 2:15: “Stand firm and hold to the traditions you were taught by us, whether by word of mouth or by letter” (similarly, 1 Corinthians 11:2, 2 Thessalonians 3:6). 

The early Christian Church absolutely did not follow the Bible alone, but primarily followed the oral teaching of Jesus and the Apostles. Here, St. Paul clearly exhorts us to follow both the spoken (sacred tradition) and written (sacred Scripture) sources of divine revelation God has given to us.

As the New Testament was written, Christians relied on the Church that Jesus founded to properly interpret it. Following “Scripture alone” through private interpretation of the Bible was unheard of.

Stunningly, this idea of sola scriptura is not even found in Scripture. It is unscriptural itself, and so it is self refuting!

Additionally, there is no inspired table of contents in the Bible. We cannot possibly know which books belong in the Bible from Scripture alone. It was the Church in the late 300s that discerned by the Holy Spirit which books were truly inspired by God and belonged in Scripture. For the first four centuries of Christianity, Christians didn’t even have the Bible. To be a “Bible-alone” Christian was an impossibility. On top of this, before the printing press in the 1500s, all Bibles were hand copied and prohibitively expensive. Very few could afford their own private copy, and, either way, most could not read.

But perhaps the most compelling reason to reject sola scriptura is that it simply doesn’t work – and God never intended it to. If there is one Holy Spirit, one Bible, and one set of unchanging, universal truths, how is it that we now have thousands of different Protestant denominations (some estimate well over 30,000), each with very contradictory teachings on some very important doctrines – and all stemming from radically different interpretations of the same Bible. The fruit of sola scriptura has been utter Christian disunity, in total opposition to the unity Jesus prayed for in John 17.

4) The Church is the “Pillar and Foundation of Truth”

1 Tim 3:15: “The household of God which is the church of the living God, the pillar and foundation of truth.”

How can we know truth? How can we know and properly understand the Bible, and all that Jesus and his Apostles taught? If you asked a “Bible Christian” what the pillar and foundation of truth was, they would almost certainly say, “the Bible.” But the Bible clearly says it’s the Church!

5) The Church Is Protected From Error by the Holy Spirit

2 Tim 1:13-14, 2:2: “Follow the pattern of the sound words which you have heard from me … guard the truth that has been entrusted to you by the Holy Spirit who dwells within us … what you have heard from me before many witnesses entrust to faithful men who will be able to teach others.”

Did you catch that? Guard the truth by the Holy Spirit! Entrust it to faithful men who will teach others. This is how the truths that Jesus left his Church can be passed on through the Apostles and their successors in a living way (sacred Tradition), protected from error by the Holy Spirit; this is the charism/gift of infallibility. It is a gift given to Jesus’ Church that every Christian should treasure.

See Part 2.