That’s not quite true. In the Summa Theologiae III q. 66 a.11 he says, “I answer that, As stated above Baptism of water has its efficacy from Christ’s passion, to which a man is conformed by Baptism, and also from the Holy Ghost, as first cause. Now although the effect depends on the first cause, the cause far surpasses the effect, nor does it depend on it. Consequently, a man may, without Baptism of Water, receive the sacramental effect from Christ’s Passion, in so far as he is conformed to Christ by suffering for him. Hence it is written(Apoc. vii. 14): These are they who are come out of great tribulation, and have washed their robes and have made them white in the blood of the Lamb. In like manner a man receives the effect of baptism by the power of the Holy Ghost, not only without the Baptism of Water, but also without the Baptism of Blood: forasmuch as his heart is moved by the Holy Ghost to believe in and love God and to repent of his sins: wherefore this is also called the Baptism of Repentence.”