Love never gives up, never loses faith, is always hopeful and endures through every circumstance.
-1 Corinthians 13:7
Emphasize the deep spiritual nature of a wedding with a quote from the New Testament. Traditional verses like this one allow you to celebrate religion and the role it plays in marriage even if the bride and groom don't share your faith.
At its heart, this quote simply reminds the couple that marriage takes work, optimism and commitment through good times and bad. It paints such a complete picture of marriage that there's no need to add your own sentiments or anecdotes unless you want to. A simple congratulations and a raise of the glass will complement this quote perfectly, fulfilling the toasting duties of parents, friends or other guests.