First, in Sacred Tradition. But I know that you limit the Word of God to Scripture. So, let’s go there. But first…
…you have to realize that the Catholic Church is the Church which is described in Scripture. No Protestant Church existed for another 1500 years.
First, Jesus Christ appointed a Pastor as head of the entire Church:
He saith unto him the third time, Simon, son of John, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee. Jesus saith unto him, Feed my sheep.
I see only a few Churches with such a Pastor. Further, Jesus Christ said that the Pastor over His Church would be infallible:
Matthew 16:17And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.18And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. 19And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
The list of Churches accept this teaching gets smaller. Certainly, all Protestant denominations can now be eliminated.
Jesus Christ not only said that the Pastor was infallible but Scripture describes the Church as infallible:
To the intent that now unto the principalities and powers in heavenly places might be known by the church the manifold wisdom of God,
The list remains the same, but now I can certainly eliminate all Protestant denominations.
Back to Matt 16:18, Scripture says that Jesus Christ established one Church. History shows that all the Churches sprang from the Church which is frequently described as the Mother Church. The Catholic Church.
So, even using just a few verses we can eliminate the Protestants. None of their denominations even come close to being in Scripture. But we can continue to find Catholic indicators throughout the Bible:
The Church which is infallible (1 Tim 3:15; Eph 3:10).
The Church which is united (Eph 4:5).
The doctrines of the Catholic Church which are distinctive from other churches:
Purgatory (1 Cor 3:15).
Eucharist (1 Cor 11:23-27).
Communion of Saints (Rom 12:12-20).
The Mass and the necessity to attend (Heb 10:25-31).
The Sacrament of Confession (Heb 13:17).
The Sacrament of Holy Orders (1 Tim 4:14).
The Sacrament of Baptism (Titus 3:5).
Justification and salvation by faith and works (Rom 2:1-13).
Finally, I will say, that if your church is not infallible, it isn’t led by Jesus Christ. Because Jesus Christ is infallible.