This is a strange remark on three levels. First, it wouldn't be disqualifying a theology except in the eye of some Protestant knee-jerkers. The Gospel of Jesus Christ is a gospel of works, as well as of grace:
6 [God] will render to every man according to his works. 7 To them indeed, who according to patience in good work, seek glory and honour and incorruption, eternal life: 8 But to them that are contentious, and who obey not the truth, but give credit to iniquity, wrath and indignation. 9 Tribulation and anguish upon every soul of man that worketh evil, of the Jew first, and also of the Greek. 10 But glory, and honour, and peace to every one that worketh good, to the Jew first, and also to the Greek.(Romans 2)
17 So faith also, if it have not works, is dead in itself. 18 But some man will say: Thou hast faith, and I have works: shew me thy faith without works; and I will shew thee, by works, my faith. 19 Thou believest that there is one God. Thou dost well: the devils also believe and tremble. 20 But wilt thou know, O vain man, that faith without works is dead? 21 Was not Abraham our father justified by works, offering up Isaac his son upon the altar? 22 Seest thou, that faith did co-operate with his works; and by works faith was made perfect? 23 And the scripture was fulfilled, saying: Abraham believed God, and it was reputed to him to justice, and he was called the friend of God. 24 Do you see that by works a man is justified; and not by faith only?
(James 2)
Second, liturgical works are not commonly understood as works: these are gifts of grace.
Heal the sick, raise the dead, cleanse the lepers, cast out devils: freely have you received, freely give(Matthew 10:8)
Lastly, the sacramental ecclesiology is plain gospel -- call it what you will.
Do penance, and be baptized every one of you in the name of Jesus Christ, for the remission of your sins: and you shall receive the gift of the Holy Ghost(Acts 2:38)
baptism being of the like form [of water], now saveth you also
(1 Peter 3:21)
16 The chalice of benediction, which we bless, is it not the communion of the blood of Christ? And the bread, which we break, is it not the partaking of the body of the Lord? 17 For we, being many, are one bread, one body, all that partake of one bread
(1 Cor. 10)
54 ... Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you. 55 He that eateth my flesh, and drinketh my blood, hath everlasting life: and I will raise him up in the last day. 56 For my flesh is meat indeed: and my blood is drink indeed. 57 He that eateth my flesh, and drinketh my blood, abideth in me, and I in him. 58 As the living Father hath sent me, and I live by the Father; so he that eateth me, the same also shall live by me.
(John 6)
Do penance, and be baptized every one of you in the name of Jesus Christ, for the remission of your sins: and you shall receive the gift of the Holy Ghost
(Acts 2:38)
The text does not say, "Do penance", which is a Roman perversion in translation. It says, "Repent".
Penance as is defined by Roman Catholicism is to atone for the sins Roman Catholics commit after baptism.
Penance is a denial of the Atonement of Christ to have paid the full penalty for all the sins of the Elect.
Penance is works righteousness and will not get anyone into heaven. On the contrary, like the Pharisees, it is a rejection of the Precious Blood of Christ, in lieu of man made religious rituals.