Did God leave all mankind to perish in a state of sin and misery?

Answer

God having, out of his good pleasure from all eternity, elected some to everlasting life (), entered into a covenant of grace to deliver them out of the state of sin and misery, and to bring them into a state of salvation by a Redeemer ().

Read the 2 proof texts (KJV)

2 Thessalonians 2:13: But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:
Romans 5:21: That as sin hath reigned unto death, even so might grace reign through righteousness unto eternal life by Jesus Christ our Lord.