Do Roman Catholics believe only grace gets us into heaven?
Baptism introduces us into the life of the triune God, and incorporates us into Christ’s body, the Church, which gives us a share in his dying and rising. Justified and sanctified by baptism, we are able to give praise and worship to God. Through the Holy Spirit received in baptism, the Christian is able to recognize and receive the teaching of the apostles and, through the means of grace (the sacraments), strive to obey all Jesus commanded, especially to serve him in the poor.
Emphasis added. The Very Rev. Thomas A. Baima, S.T.D., Vice Rector for Academic Affairs, Dean of the Graduate School of Theology, University of Saint Mary of the Lake, Mundelein Seminary. "From the Horse's Mouth: What is the Meaning and Purpose of Baptism?" Creedo Magazine. Volume 4, Issue 2, April 2014, 8. Available online at http://www.credomag.com/issues/Churchy%20Gimmicks.pdf.
By way of the best contrast presented in the article, consider the Anglican position:
For Anglicans, baptism is an outward and visible sign of an inward and spiritual grace. Water baptism is an outward sign of cleansing to indicate an inward cleansing of the Spirit (Heb. 10:22). The meaning of baptism is grounded in Jesus’ use of water to make and mark his disciples (John 4:1-2; Matt. 28:19-20). Its purpose is therefore to mark a new beginning, signifying that the disciple has been made clean through God’s Word and by his Spirit, using water as a visible sign of such cleansing (John 13:10; Eph. 5:26).
The Most Rev. Dr. Glenn Davies, Anglican Archbishop of Sydney, Australia, PhD, Sheffield. Ibid.