Romans 5:5

and hope putteth not to shame; because the love of God hath been shed abroad in our hearts through the Holy Spirit which was given unto us. "putteth not to shame" -it does not deceive, it does not mock us, it is not disappointed. (Erdmans p. 70)

The person who trusts in Jesus will not be disappointed (1 Peter 2:6). But those who put their trust in other things, will be (1 Peter 3:16; Luke 12:20). "All other hopes put to shame; they do not rest on realities. The heart that held such false hopes is filled with shame, with everlasting shame." [Note: Lenski p. 339]

"because" -the reason that we are so certain that this our hope will not disappoint us.

"love of God" -from the context (Romans 5:6ff), the love that God has for us.

"shed abroad" -'poured out' (NASV); 'has been poured out in, and still floods' (Gr. Ex. N.T. p. 624)

From the context it appears that 'God's love for us' was poured into our hearts, through the gospel message revealed by the Holy Spirit. It was the Holy Spirit Who delivered the message found in verses 6-11. We are assured of our hope, because the God that so lovingly gave His only Son for us, will certainly deliver on the rest of His promises!

"who was given to us" -be careful about jumping to the conclusion that this passage is. teaching. personal indwelling of the Spirit. The Spirit was 'given' to reveal the gospel message (a message about God's love for us),. message that in the final analysis only really benefits those that embrace it (Christians) (Ephesians 3:3)