It means I believe in His holy Church, to which He transmitted His authority.  To believe in Jesus Christ means, furthermore, to believe in His Passion and death, by which He redeemed the world; in His glorious resurrection and ascension.  He is the Divine Master, and as such the supreme Lawgiver whom all creatures must obey.  He is also the Judge of the universe, and as such will come again one day to preside at the general judgment, when He will judge all men according to their belief, according to the manner in which each one has observed or transgressed His commandments, used or neglected the means of salvation.  Then will be the end of time; and mankind will go to its reward or to its punishment once and for all.  All this is proclaimed in the articles of faith that treat of Jesus Christ.  To believe in Jesus Christ means to believe everything that the Gospel teaches and everything which the holy, infallible Church requires us to believe.

The third chief part of the Creed declares what we must believe of the Holy Ghost, the third Person of the Godhead.

III.  The Holy Ghost, the third Person of the Godhead, proceeds equally from the Father and the Son, from all eternity, and is of equal essence with the Father and the Son from eternity.

The Holy Ghost, sent by the Father and the Son, came down upon earth and took charge of the Church founded by Christ, in order to apply through it the fruits of redemption to mankind.

Only in the true Church of Christ can be found the fruits of the redemption; only in her is the true priesthood of the Lord.  The fruits of the redemption here on earth are truth and grace, and in the hereafter eternal salvation.  The divine truth, as proclaimed by Christ, is alone contained in the holy Catholic Church; and through the co-operation of the Holy Ghost it is preserved uncorrupted in this Church.  The Church is the pillar and the beacon of the truth.  She can not deviate unto the end of the world one tittle from the doctrine received from Christ, because the Holy Ghost guides the teaching Church in all truth, and sees to it that every truth is understood rightly by her and properly interpreted and explained.  Hence, to submit ourselves to the Church’s definition of the faith means to submit ourselves to the Holy Ghost.  The Holy Ghost operates in the Church, through the priesthood, and thus applies to the faithful the fruits of the redemption, so as to sanctify them and prepare them for eternal happiness.  Thus it is the Holy Ghost who sanctifies us, who makes us holy, as our Father in heaven is holy; who leads us to perfection, as our Father in heaven is perfect.