Some Christians interpret Bible differently - verses that suggest Jesus' sacrifice is intended for all people- John 3:16 - speaks of God's love for the world- 1 Timothy 2:4-6 talks about God desiring all to be saved.
How is humanresponsibility a weakness?
Emphasis importance of human responsibility and freewill in responding to God's offer of salvation. God's grace is extended to all and it is up to the individual to accept or reject it through their fate.
How is universal Love of God a weakness?
God's love is universal and not selected to a preselected group. God's desire for all humanity saved is consistent with his character- loving and just God