Is a Catholic allowed to marry a non-Christian? I know Scripture states not to be unequally yoked with unbelievers.

The Catholic Church calls this situation “disparity of cult,” and there are circumstances in which it may be allowed. Here is what the Catechism of the Catholic Church teaches about disparity of cult and mixed marriage (marriage between a Catholic and a baptized non-Catholic):

Difference of confession between the spouses does not constitute an insurmountable obstacle for marriage . . . But the difficulties of mixed marriages must not be underestimated . . . The spouses risk experiencing the tragedy of Christian disunity even in the heart of their own home. Disparity of cult can further aggravate these difficulties. Differences about faith and the very notion of marriage, but also different religious mentalities, can become sources of tension in marriage, especially as regards the education of children. The temptation to religious indifference can then arise.
According to the law in force in the Latin Church, a mixed marriage needs for liceity the express permission of ecclesiastical authority. In case of disparity of cult an express dispensation from this impediment is required for the validity of the marriage. This permission or dispensation presupposes that both parties know and do not exclude the essential ends and properties of marriage; and furthermore that the Catholic party confirms the obligations, which have been made known to the non-Catholic party, of preserving his or her own faith and ensuring the baptism and education of the children in the Catholic Church. (CCC 1634-1635)