When called to give a brief account of my Catholic Faith, here is what I go with. It is the basic core of what we believe as Catholics, what is called the "Kerygma." You'll find slightly different lists with different emphases out there, but here is what I go with. I back up each point with a scripture verse for apologetic reasons.
1) God loves us all (Rom 5:8) and wants all men to be saved (1 Tim 2:4)
2) But we all have sinned (1 Jn 1:8) & and wages of sin is death (Rom 6:2) and separation from God (Mt 7:23)
3) Christ died for us so we can live forever with Him (1 Cor 15:3-8). He paid the price none of us could.
4) This demands a response from us. We must Repent of our sins and and Believe in the
Gospel (Mk 1:15)
5) But this is not the end, it is just the
beginning of life in Christ, who we must abide in (Jn 15:5) by being
apart of the One Church He founded - the Catholic Church - on Peter
(Mt 16:18), the Apostles (Mt 18:18) and their successors (Acts 1:20) until the end of the world (Mt 28:20)
6) We do this by obeying Christ's teaching (Jn 14:21),
the teaching of the Church (Lk 10:16) and by receiving the Sacraments,
especially Baptism to enter the Body of Christ (Acts 2:38), the Eucharist to remain in the Body of Christ (Jn 6:53-54), and Confession to be rid of our sins (Jn 20:23).
A shorter version (without quoting) Scripture would be:
1) God loves everyone
2) We all have sinned
3) God became man and died for us in Jesus Christ
4) We must repent and believe to accept God into our lives
5) That's not the end! We must abide in Christ and His Holy Church
6) We do this by obeying Christ's teachings and living a Sacramental life