The Israelites were commanded to bring the firstfruits of their harvest to God as an offering, something which required obedience and trust that God would provide from the rest of their crops all that they needed. In the same way, the Holy Spirit is a promise of what is to come (Eph 1:13-14). The Greek word ‘arrabon’ means something given in security, a pledge or deposit. Once given, a person was legally obliged to complete the purchase; the deposit was a foretaste of something much greater to come.
We are fortunate to have a coffee machine with a programmable timer, so we often wake in the morning to the delicious aroma of coffee. The smell is a draw, inviting us to come and taste the drink.
In the same way, the Holy Spirit works in our lives to draw us to Christ and to promise us even greater things in Him. This requires patience (see Rom 8:22-25), and God often requires us to wait far longer than we would like! – but we can be sure that our adoption to sonship is secure and that God is working in all things for our good. (Rom 8:28) We have been brought into the family of God, and all He requires from us now is our yielded obedience and service to Him.