We must be made "perfect in holiness" and "irreproachable at the coming of our Lord Jesus Christ" (1 Thes 5:23). The Lord is returning to find "a glorious Church, holy and immaculate, without stain or wrinkle or anything of that sort" (Eph 5:27). If we are to see the Lord face to face in heaven (Heb 12:14), we must become immaculate and holy in every aspect of our conduct (1 Pt 1:15).
We become holy and immaculate by being baptized into Christ and receiving a new nature. When we sin after receiving a new life in Christ, we can become immaculately retrieved by repenting of our sins, confessing them, and accepting God's forgiveness. Through a life in Christ of resisting temptations, repenting of sins, and being purified, we become immaculate. If we have totally given our lives to Jesus but have not become immaculate by the time we die, we will be made immaculate in purgatory after death. If we are to see the Lord in heaven, we must be made immaculate by His grace (Heb 12:14).
Today's solemn feast day, the Immaculate Conception of Mary, shows us both the necessity and the hope of becoming immaculate. The Lord made Mary immaculate from her conception. This encourages us to believe that He will make us immaculate after our conceptions, throughout our lives, and before or, if necessary, after our deaths.
"O Mary, conceived without sin, pray for us who have recourse to you."