In an article by Fr. Benito Martínez, C.M., we read:

“There is no doubt that the faith of Louise de Marillac encompassed those Christian truths that were obligatory in order to be a member of the Holy Roman Catholic and Apostolic Church… Louise understood these truths as a commitment to the living God with whom she had established a relationship. Louise’s spirituality was not some doctrine but involved clothing herself in the Spirit of Jesus Christ (as she had been taught by her spiritual director, Vincent de Paul). But God is the Trinity and we see how her faith introduced her to each one of the divine persons…”

Read more in the presentation below.

Additional reading

Here are the notes written by St. Louise during a retreat, mentioned by the author on Slide 8 (emphasis added):

The subject of my sixth meditation was the marks which Our Lord gives so that one may know if one has received the Holy Spirit. The strong and tender love of Our Lord appeared clearly when He told His Apostles of the consolation that the coming of the Holy Spirit would afford them.. He revealed the two forms that this consolation would take. The first was that the Holy Spirit would bear witness to Him. O my Savior, had You not given them enough by Your words and works both during Your lifetime and after Your Resurrection? What more could the Spirit of Consolation, whom the Father would send by You, do for them? O profound and inscrutable secret! O Trinity perfect in power, wisdom, and love! You bring to completion the work of founding the .Holy Church. You desire her to be the Mother of all believers. To this end, You console her by instructing and strengthening her in the truths which the Incarnate Word had taught her. You infused into this Mystical Body the union of your works, giving her the power to perform miracles so as to enable her to bring to souls the true witness which You willed her to bear to Your Son. You operated in them holiness of life by the merits of the Word Incarnate. The Holy Spirit, by means of His unitive love, associates Himself to this action in order to produce the same effects by His coming. He thus renders to men the proof of the divinity and perfect manhood of Christ which should be for all a source of joy, emulation, and true detachment from worldly affections so as to form oneself according to His holy and divine actions which should lead to the resolution to live as reasonable human beings. I believe that this is what Our Lord wished to convey to His Apostles when He told them that, after the coming of the Holy Spirit, they would also bear witness to Him. This is what all Christians must do, not by bearing witness to the doctrine of Christ, which is the prerogative of apostolic men, but by the perfect actions of true Christians. Blessed are those persons who, under the guidance of Divine Providence, are called upon to continue the ordinary practices of the life of the Son of God through the exercise of charity.

O Holy Spirit, you alone can enlighten us concerning the greatness of this mystery which, if one can say such a thing, reveals the impatience of God seen in the promptness with which He carried out His design on human nature for the perfection of the union which His omnipotence wished to operate in it. O creatures blinded by trifles, and I more than any other! Let us lift our spirits, not above what we are in the plan of God, that would be impossible, but above our natural inclinations which are due to the corruption of sin, so that in all our actions we may honor Our Lord by the witness He wishes us to bear to Him by performing the actions which He accomplished on earth and to which, on account of His love for us, He will apply the merits of His own. He wills by this means that Christians experience in this life that union with God which He has merited for us.

To this end, I shall strive, with the help of His grace, to overcome my sloth and to make use of a practice which was recommended in a reading: to look upon all the occasions for doing some good for my neighbor not only in terms of the recompense which Our Lord has promised to me: because He considers such acts as done to Himself, but also in light of the fact that the neighbor has been given to me in the place of Our Lord, by means of a love which His goodness knows and which He has revealed to my heart, although I am unable to put it into words.

I shall also make use of a thought which His goodness gave me at a moment when I was distracted by a vain consideration; namely, that when I am seen accomplishing some good deed, I shall develop the habit of calling to mind the belief that God and His angels are watching me.

(Spiritual Writings of St. Louise, p. 820-821)