The Crusades and the Templars can be said to have reinforced the ideology of feudalism by connecting the feudal elites more closely to the Church and to religion. One aspect of the ideology of feudalism was the contention that the feudal order was mandated by God. The fact that the elite levels of feudal society were willing to risk their lives and their fortunes to take the cross and defend Christianity (as people at the time saw the Crusades) would have given the system more credibility in the eyes of the people.
In the short term, the Crusades and Templars bolstered the power of the Church. In the long term, though, they can be said to have eroded it. The Crusades ultimately failed, which undermined the prestige of the Church that kept ordering them. The dissolution of the Templar order made the Church look bad both because of the accusations made against the Templars and because of the fact that the Church was seen to acquiesce in the persecution of an order that was, in fact, innocent of the charges against it.