"Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ." - Ephesians 1:3
All of God's blessings are received "in Christ." That means to be in union with Christ. It is a faith union, when we believe on the Lord Jesus Christ. It is a spiritual union. Every believer is sealed with the Holy Spirit after trusting in Christ (Ephesians 1:13).
Every blessing God has for the believer is in Christ. We do not earn God's blessings by our works, rather all the blessings of God are for believers through the finished work of Christ at the cross. Therefore, the blessings of God come to us by grace alone in Christ alone.
The Lord Jesus Christ is in heaven as the believer's Mediator, Intercessor, and Advocate with God the Father (1 Timothy 2:5; Hebrews 7:25; 1 John 2:1-2). For this reason God the Father "has blessed us with every spiritual blessing in the heavenly places in Christ."
Because "God is Spirit" (John 4:24), they are spiritual blessings applied to believers through the Holy Spirit. God the Father "has blessed us with every spiritual blessing." In essence, God is a spiritual being who blesses all of His people.
Immediately upon believing on the Lord Jesus Christ, we are adopted into the family of God (Ephesians 1:5), and "in Him we have received an inheritance" (Ephesians 1:11). Many blessings come now, but the best is yet to come in our inheritance. God "has blessed us" now, with much greater blessings to come. Every believer is "an heir of God through Christ" (Galatians 4:7).